Update RFC filename and PR link

Signed-off-by: Derek Richard <[email protected]>

Author: drich10

toc/rfc/rfc-0040-shared-concourse.md renamed to toc/rfc/rfc-draft-shared-concourse.md

@@ -4,7 +4,7 @@
 - Start Date: 2025-07-07
 - Author(s): @drich10
 - Status: Draft
-- RFC Pull Request: (fill in with PR link after you submit it)
+- RFC Pull Request: https://github.com/cloudfoundry/community/pull/1238
 
 ## Summary