docs: Clarify commit access requirements in the Developer Policy (#101414)

We have been discussing changes to our commit access polices recently
and based on some feedback from clattner here:

https://discourse.llvm.org/t/rfc-new-criteria-for-commit-access/76290/81

We need to update our Developer Policy so that it matches what we are
actually doing in this project. We currently grant commit access to
anyone with a valid justification, not just contributors who have
submitted high-quality patches in the past.

---------

Co-authored-by: Shilei Tian <[email protected]>

Author: tstellar

llvm/docs/DeveloperPolicy.rst

@@ -475,8 +475,8 @@ What are the expectations around a revert?
 Obtaining Commit Access
 -----------------------
 
-We grant commit access to contributors with a track record of submitting high
-quality patches.  If you would like commit access, please send an email to
+We grant commit access to contributors that can provide a valid justification.
+If you would like commit access, please send an email to
 `Chris <mailto:[email protected]>`_ with your GitHub username.  This is true
 for former contributors with SVN access as well as new contributors. If
 approved, a GitHub invitation will be sent to your GitHub account. In case you