Add a mention about library managers 24 hour update cycle

docs/librarymanager/creating.rst

@@ -20,6 +20,9 @@ source code structure. The only one requirement is library's manifest file -
 :ref:`library_config`. It can be located inside your library or in the another
 location where |PIOAPICR| will have *HTTP* access.
 
+Updates to existing libraries are done every 24 hours. In case a more urgent
+update is required, you can post a request on PlatformIO `community <https://community.platformio.org/>`_.
+
 .. contents::
 
 Source Code Location