manual: Don't number the list 1. 1. 1.

Even though it renders correctly it's confusing for anyone reading the
text version.

doc/manual/manual.md

@@ -5069,12 +5069,12 @@ At this step the built-ins in question are marked for a deprecation warning.
 They remain available by default, but referring to them will trigger a
 warning.
 
-1. The objects in question are made invisible by default.
+2. The objects in question are made invisible by default.
 Now, referring to the affected built-ins will fail unless the
 `enable_deprecated` command is used.
 In that case referring to them will still produce a warning.
 
-1. The objects in question are removed entirely and are no longer
+3. The objects in question are removed entirely and are no longer
 available.
 
 In general any object or group of objects will move only one step per