Minor gRPC docs updates

docs/sources/next/javascript-api/k6-net-grpc/client/client-invoke.md

@@ -16,7 +16,7 @@ error will be thrown.
 | Parameter         | Type   | Description                                                                                                                                                                 |
 | ----------------- | ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | url               | string | The gRPC method url to invoke, in the form `/package.Service/Method`, e.g. `/google.cloud.language.v1.LanguageService/AnalyzeSentiment`. The leading slash `/` is optional. |
-| request           | object | The canonical request object, as-per the [Protobuf JSON Mapping](https://developers.google.com/protocol-buffers/docs/proto3#json).                                          |
+| request           | object | The canonical request object, as-per the [Protobuf JSON Mapping](https://grafana.com/docs/k6/<K6_VERSION>/using-k6/protocols/grpc/#protocol-buffers-json-mapping).          |
 | params (optional) | object | [Params](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-net-grpc/params) object containing additional request parameters.                                       |
 
 ### Returns

docs/sources/next/javascript-api/k6-net-grpc/stream/stream-write.md

@@ -6,7 +6,7 @@ weight: 40
 
 # Stream.write()
 
-Writes a message to the stream.
+Writes a message to the stream. The message is a canonical request object, as-per the [Protobuf JSON Mapping](https://grafana.com/docs/k6/<K6_VERSION>/using-k6/protocols/grpc/#protocol-buffers-json-mapping).
 
 ### Example
 

docs/sources/next/using-k6/protocols/grpc.md

@@ -89,7 +89,7 @@ export default () => {
 
 In server streaming mode, the client sends a single request to the server, and the server replies with multiple responses.
 
-The example below demonstrates client streaming.
+The example below demonstrates server streaming.
 
 {{< code >}}
 
@@ -256,11 +256,15 @@ stream.on('error', function (e) {
 
 {{< /code >}}
 
-### Handle special cases in message Marshaling/Unmarshaling
+### Protocol Buffers JSON Mapping
+
+It's important to note how k6 handles requests and messages. First, it tries to marshal the request/message in JSON format. Then, k6 uses the [protojson](https://pkg.go.dev/google.golang.org/protobuf/encoding/protojson) package to encode or decode to a Protobuf message.
+
+A limitation during this process is that the object you pass as a request/message must be serializable. That means structs like `Map` don't work.
 
-k6 uses the [protojson](https://pkg.go.dev/google.golang.org/protobuf/encoding/protojson) package for encoding and decoding of messages.
+The benefit of using `protojson` is the canonical JSON encoding support. The [Protocol Buffers documentation](https://protobuf.dev/programming-guides/proto3/#json) describes this mapping.
 
-Certain gRPC well-known types or wrappers have specific marshaling/unmarshaling rules.
+#### Examples
 
 For instance, if you import `"google/protobuf/wrappers.proto"` and your proto-definitions look like this:
 
@@ -301,7 +305,7 @@ if (respInt.message !== '6') {
 
 {{< /code >}}
 
-Another special case could be usage of `oneof`. Let's say you have a proto-definition like this:
+Another example could be usage of `oneof`. Let's say you have a proto-definition like this:
 
 ```proto
 syntax = "proto3";

docs/sources/v0.49.x/javascript-api/k6-net-grpc/client/client-invoke.md

@@ -16,7 +16,7 @@ error will be thrown.
 | Parameter         | Type   | Description                                                                                                                                                                 |
 | ----------------- | ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | url               | string | The gRPC method url to invoke, in the form `/package.Service/Method`, e.g. `/google.cloud.language.v1.LanguageService/AnalyzeSentiment`. The leading slash `/` is optional. |
-| request           | object | The canonical request object, as-per the [Protobuf JSON Mapping](https://developers.google.com/protocol-buffers/docs/proto3#json).                                          |
+| request           | object | The canonical request object, as-per the [Protobuf JSON Mapping](https://grafana.com/docs/k6/<K6_VERSION>/using-k6/protocols/grpc/#protocol-buffers-json-mapping).          |
 | params (optional) | object | [Params](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-net-grpc/params) object containing additional request parameters.                                       |
 
 ### Returns

docs/sources/v0.49.x/javascript-api/k6-net-grpc/stream/stream-write.md

@@ -6,7 +6,7 @@ weight: 40
 
 # Stream.write()
 
-Writes a message to the stream.
+Writes a message to the stream. The message is a canonical request object, as-per the [Protobuf JSON Mapping](https://grafana.com/docs/k6/<K6_VERSION>/using-k6/protocols/grpc/#protocol-buffers-json-mapping).
 
 ### Example
 

docs/sources/v0.49.x/using-k6/protocols/grpc.md

@@ -89,7 +89,7 @@ export default () => {
 
 In server streaming mode, the client sends a single request to the server, and the server replies with multiple responses.
 
-The example below demonstrates client streaming.
+The example below demonstrates server streaming.
 
 {{< code >}}
 
@@ -256,11 +256,15 @@ stream.on('error', function (e) {
 
 {{< /code >}}
 
-### Handle special cases in message Marshaling/Unmarshaling
+### Protocol Buffers JSON Mapping
+
+It's important to note how k6 handles requests and messages. First, it tries to marshal the request/message in JSON format. Then, k6 uses the [protojson](https://pkg.go.dev/google.golang.org/protobuf/encoding/protojson) package to encode or decode to a Protobuf message.
+
+A limitation during this process is that the object you pass as a request/message must be serializable. That means structs like `Map` don't work.
 
-k6 uses the [protojson](https://pkg.go.dev/google.golang.org/protobuf/encoding/protojson) package for encoding and decoding of messages.
+The benefit of using `protojson` is the canonical JSON encoding support. The [Protocol Buffers documentation](https://protobuf.dev/programming-guides/proto3/#json) describes this mapping.
 
-Certain gRPC well-known types or wrappers have specific marshaling/unmarshaling rules.
+#### Examples
 
 For instance, if you import `"google/protobuf/wrappers.proto"` and your proto-definitions look like this:
 
@@ -301,7 +305,7 @@ if (respInt.message !== '6') {
 
 {{< /code >}}
 
-Another special case could be usage of `oneof`. Let's say you have a proto-definition like this:
+Another example could be usage of `oneof`. Let's say you have a proto-definition like this:
 
 ```proto
 syntax = "proto3";