doc: explain how to deactivate submodule.recurse completely

Signed-off-by: Damien Robert <damien.olivier.robert+git@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config/submodule.txt

@@ -63,6 +63,13 @@ submodule.recurse::
 	(`checkout`, `fetch`, `grep`, `pull`, `push`, `read-tree`, `reset`,
 	`restore` and `switch`) except `clone` and `ls-files`.
 	Defaults to false.
+	When set to true, it can be deactivated via the
+	`--no-recurse-submodules` option. Note that some Git commands
+	lacking this option may call some of the above commands affected by
+	`submodule.recurse`; for instance `git remote update` will call
+	`git fetch` but does not have a `--no-recurse-submodules` option.
+	For these commands a workaround is to temporarily change the
+	configuration value by using `git -c submodule.recurse=0`.
 
 submodule.fetchJobs::
 	Specifies how many submodules are fetched/cloned at the same time.