perlapi: Document SvUVXx()

I'm doing so because Devel::PPPort provides this function.

1 files changed, 3 insertions, 0 deletions

diff --git a/sv.h b/sv.h
index 56a7cc50dc..e0d37e7fd5 100644
--- a/sv.h
+++ b/sv.h
@@ -766,6 +766,9 @@ Only use when you are sure C<SvIOK> is true.  See also C<L</SvIV>>.
 Returns the raw value in the SV's UV slot, without checks or conversions.
 Only use when you are sure C<SvIOK> is true.  See also C<L</SvUV>>.
 
+=for apidoc AmD|UV|SvUVXx|SV* sv
+This is an unnecessary synonym for L</SvUVX>
+
 =for apidoc Am|NV|SvNVX|SV* sv
 Returns the raw value in the SV's NV slot, without checks or conversions.
 Only use when you are sure C<SvNOK> is true.  See also C<L</SvNV>>.