general-concepts/ebuild-revisions: mention balancing examples against…

… stable

Explicitly say that even 'no revision bump' examples should be balanced
against whether a stable ebuild is being modified, as we want to minimize
any risk of regressions there.

i.e. It might be that a change would not need a revbump for an ~arch-only
ebuild, but if the ebuild is stable, the principle of being conservative
ofr stable would mean a revbump is warranted.

general-concepts/ebuild-revisions/text.xml

@@ -125,6 +125,9 @@ of thumb could be used as a guideline:
  </li>
 </ul>
 
+Note that the examples above should still be balanced against the general
+principle of conservatism and need to minimize risk for stable users.
+
 </body>
 </chapter>
 </guide>