link to docs to rebase a pull request

docs/en_us/developers/source/process/core-committer.rst

@@ -12,7 +12,7 @@ there are a few ways that the process is different:
 * The contributor cannot see when conflicts occur in the branch.
   These conflicts prevent the pull request from being merged,
   so you should ask the contributor to rebase their pull request,
-  and point them to the documentation for doing so.
+  and point them to `the documentation for doing so`_.
 
 * Jenkins may not run on the contributor’s pull request automatically.
   Be sure to start new Jenkins jobs for the PR as necessary -- do not approve
@@ -30,6 +30,8 @@ there are a few ways that the process is different:
   -- if you think the pull request should be closed, inform the
   community managers, and they will handle it.
 
+.. _the documentation for doing so: https://github.com/edx/edx-platform/wiki/How-to-Rebase-a-Pull-Request
+
 Each Scrum team should decide for themselves how to estimate stories related to
 reviewing external pull requests, and how to claim points for those stories,
 keeping in mind that an unresponsive contributor may block the story in ways