Merge pull request #489 from jab/jab-docs

more small tutorial fixes (take 2)

docs/source/tutorial.rst

@@ -758,7 +758,7 @@ this frustrating.
 But from trio's point of view, the problem with the GIL isn't that it
 restricts parallelism. Of course it would be nice if Python had better
 options for taking advantage of multiple cores, but that's an
-extremely difficult problem to solve, and in the mean time there are
+extremely difficult problem to solve, and in the meantime there are
 lots of problems where a single core is totally adequate – or where if
 it isn't, then process- or machine-level parallelism works fine.
 
@@ -841,10 +841,12 @@ An echo client
 
 The traditional application for demonstrating network APIs is an "echo
 server": a program that accepts arbitrary data from a client, and then
-sends that same data right back. Probably a more relevant example
+sends that same data right back. (Probably a more relevant example
 these days would be an application that does lots of concurrent HTTP
-requests, but trio doesn't have an HTTP library yet, so we'll stick
-with the echo server tradition.
+requests, but for that `you need an HTTP library
+<https://github.com/python-trio/trio/issues/236#issuecomment-310784001>`__
+such as `asks <https://asks.readthedocs.io>`__, so we'll stick
+with the echo server tradition.)
 
 To start with, here's an example echo *client*, i.e., the program that
 will send some data at our echo server and get responses back: