Improve 'Push Merge Commit' access right documentation

In the documentation the 'Push Merge Commit' access right was named
'Push Merge'. Correct the name to be consistent with the name that is
displayed in the Gerrit WebUI.

In addition remove the link to the 'Push' access right from the
documentation of the error 'you are not allowed to upload merges'.
When the user gets this error he has already the 'Push' access right
assigned and only 'Push Merge Commit' is missing. If 'Push' would be
missing the user would get an 'Upload Denied' error. Also the
'Push Merge Commit' documentation explains that it requires 'Push'.
This means just having the link to 'Push Merge Commit' should be
sufficiant for the 'you are not allowed to upload merges' error
description.

Change-Id: Idfec58e52ba77c967abb97deb6cc90f42c3395d9
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/Documentation/access-control.txt b/Documentation/access-control.txt
index 103bbaa..70c58a2 100644
--- a/Documentation/access-control.txt
+++ b/Documentation/access-control.txt
@@ -619,15 +619,15 @@
 
 
 [[category_push_merge]]
-Upload Merge Commits
+Push Merge Commits
 ~~~~~~~~~~~~~~~~~~~~
 
-The `Push Merge` permits the user to upload merge commits. It's an
-addon to the `Push` permission, and so it won't be sufficient
-with only `Push Merge` granted for a push to happen.  Some projects
-wish to restrict merges to being created by Gerrit. By granting
-`Push` without `Push Merge`, the only merges that enter the
-system will be those created by Gerrit.
+The `Push Merge Commit` permits the user to upload merge commits.
+It's an addon to the <<category_push,Push>> access right, and so it
+won't be sufficient with only `Push Merge Commit` granted for a push
+to happen.  Some projects wish to restrict merges to being created by
+Gerrit. By granting `Push` without `Push Merge Commit`, the only
+merges that enter the system will be those created by Gerrit.
 
 
 [[category_push_annotated]]
@@ -802,7 +802,7 @@
 |Push Branch +3 (refs/tags/*) |<<category_push_direct,Push>> (with force on refs/tags/...)
 |Read +1                      |<<category_read,Read>>
 |Read +2                      |<<category_read,Read>> & <<category_push_review,Push>> (refs/for/refs/...)
-|Read +3                      |<<category_read,Read>> & <<category_push_review,Push>> (refs/for/refs/...) & <<category_push_merge,Push merge>>
+|Read +3                      |<<category_read,Read>> & <<category_push_review,Push>> (refs/for/refs/...) & <<category_push_merge,Push Merge Commit>>
 |Submit                       |<<category_submit,Submit>>
 |=================================================================================