bug#52500: misleading description of %reldir%

[Karl Berry]

Hi Bruno,

    %reldir% without a following slash expands to a dot, and
    %canon_reldir% without a following underscore expands to an underscore.

    Suggested new text:

       A special feature is that if the fragment is in the same directory
       as the base Makefile.am (i.e., %reldir% is .), then
         - %reldir% together with a following slash will expand to empty,
         - %canon_reldir% together with a following underscore will expand
           to empty as well.

Thanks much. I added the dot/underscore information you wrote as well.
I pushed it, hope it looks ok ... -k

@@ -10911,12 +10911,20 @@ Similarly, @code{%canon_reldir%} is replaced with the 
canonicalized
 is a synonym for @code{%canon_reldir%}.
 
 A special feature is that if the fragment is in the same directory as
-the base @file{Makefile.am} (i.e., @code{%reldir%} is @code{.}), then
-@code{%reldir%} and @code{%canon_reldir%} will expand to the empty
-string as well as eat, if present, a following slash or underscore
-respectively.
+the base @file{Makefile.am} (i.e., @code{%reldir%} is @code{.}), then:
+
+@table @code
+@item %reldir%
+together with a following slash expands to the empty string, otherwise
+it expands to a dot;
+
+@item %canon_reldir%
+together with a following underscore expands to the empty string, otherwise
+it expands to an underscore.
+
+@end table