config: fix indentation of some`share-safe` options

This makes the output much more readable.

mercurial/helptext/config.txt

@@ -2171,9 +2171,9 b' Alias definitions for revsets. See :hg:`'
     ``allow``
     Respects the feature presence in the share source
     ``upgrade-abort``
-    tries to upgrade the share to use share-safe; if it fails, aborts
+        Tries to upgrade the share to use share-safe; if it fails, aborts
     ``upgrade-allow``
-    tries to upgrade the share; if it fails, continue by
+        Tries to upgrade the share; if it fails, continue by
     respecting the share source setting
 
     Check :hg:`help config.format.use-share-safe` for details about the
@@ -2199,9 +2199,9 b' Alias definitions for revsets. See :hg:`'
     ``allow``
     Respects the feature presence in the share source
     ``downgrade-abort``
-    tries to downgrade the share to not use share-safe; if it fails, aborts
+        Tries to downgrade the share to not use share-safe; if it fails, aborts
     ``downgrade-allow``
-    tries to downgrade the share to not use share-safe;
+        Tries to downgrade the share to not use share-safe;
     if it fails, continue by respecting the shared source setting
 
     Check :hg:`help config.format.use-share-safe` for details about the