Document fork safety (#1433)

Author: adriandole

src/libmongoc/doc/mongoc_client_session_t.rst

@@ -11,6 +11,10 @@ Synopsis
 
 .. include:: includes/session-lifecycle.txt
 
+Fork Safety
+-----------
+A :symbol:`mongoc_client_session_t` is only usable in the parent process after a fork. The child process must call :symbol:`mongo_client_reset` on the ``client`` field.
+
 Example
 -------
 

src/libmongoc/doc/mongoc_client_t.rst

@@ -32,6 +32,10 @@ Thread Safety
 
 ``mongoc_client_t`` is *NOT* thread-safe and should only be used from one thread at a time. When used in multi-threaded scenarios, it is recommended that you use the thread-safe :symbol:`mongoc_client_pool_t` to retrieve a ``mongoc_client_t`` for your thread.
 
+Fork Safety
+-----------
+A :symbol:`mongoc_client_t` is only usable in the parent process after a fork. The child process must call :symbol:`mongoc_client_reset`.
+
 Example
 -------