Update git submodules

* Update plugins/hooks from branch 'master'
  - Change docs links to actual file extension (.md)
    
    See https://gerrit-review.googlesource.com/83950 for detailed context.
    
    Change-Id: If9d4f0726a0d8d3ca66f01819eeada2b53ac41be
    

plugins/hooks

diff --git a/plugins/hooks b/plugins/hooks
index ac87f18..c1705a7 160000
--- a/plugins/hooks
+++ b/plugins/hooks
@@ -1 +1 @@
-Subproject commit ac87f187034838e6cf8d5824b2e541cc9b3a0aa4
+Subproject commit c1705a739f117b9123e1d63aebf07d043afb0867