handbook: Add git switch info for shallow clones

Signed-off-by: Sergei Zhmylev <[email protected]>

documentation/content/en/books/handbook/ports/_index.adoc

@@ -683,8 +683,8 @@ If more control over the ports tree is needed or if local changes need to be mai
 Git can be used to obtain the Ports Collection.
 Refer to extref:{committers-guide}[the Git Primer, git-primer] for a detailed description of Git.
 
-We add --depth 1 to the git command line to clone the tree without obtaining the commit history, which saves time and is acceptable for most users. 
-If you have your own changes to the ports tree, or need the history for any reason, omit the --depth 1 argument below.
+We add `--depth 1` to the git command line to clone the tree without obtaining the commit history, which saves time and is acceptable for most users.
+If you have your own changes to the ports tree, or need the history for any reason, omit the `--depth 1` argument below.
 
 . Git must be installed before it can be used to check out the ports tree. If a copy of the ports tree is already present, install Git like this:
 +
@@ -726,7 +726,15 @@ If the ports tree is not available, or pkg is being used to manage packages, Git
 +
 [source,shell]
 ....
-# git -C /usr/ports switch 2023Q1
+# git -C /usr/ports switch 2023Q2
+....
++
+If the ports tree is cloned with `--depth 1`, make sure to fetch the desired branch in advance:
++
+[source,shell]
+....
+# git -C /usr/ports fetch --depth 1 origin 2023Q2:2023Q2
+# git -C /usr/ports switch 2023Q2
 ....
 ****