perlexperiment: add links to more issues

This commit also tries to put things into the same order between
experiments, and calls experiments "experiments" rather than "features".

pod/perlexperiment.pod

@@ -25,38 +25,38 @@ Modified in Perl 5.10.1, 5.12.0
 Using this feature triggers warnings in the category
 C<experimental::smartmatch>.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #13173]|https://github.com/Perl/perl5/issues/13173>.
 
 =item Pluggable keywords
 
-The ticket for this feature is
-L<[perl #13199]|https://github.com/Perl/perl5/issues/13199>.
+Introduced in Perl 5.11.2
 
 See L<perlapi/PL_keyword_plugin> for the mechanism.
 
-Introduced in Perl 5.11.2
+The ticket for this experiment is
+L<[perl #13199]|https://github.com/Perl/perl5/issues/13199>.
 
 =item Regular Expression Set Operations
 
 Introduced in Perl 5.18
 
-The ticket for this feature is
+Using this feature triggers warnings in the category
+C<experimental::regex_sets>.
+
+The ticket for this experiment is
 L<[perl #13197]|https://github.com/Perl/perl5/issues/13197>.
 
 See also: L<perlrecharclass/Extended Bracketed Character Classes>
 
-Using this feature triggers warnings in the category
-C<experimental::regex_sets>.
-
 =item Subroutine signatures
 
 Introduced in Perl 5.20.0
 
 Using this feature triggers warnings in the category
 C<experimental::signatures>.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #13681]|https://github.com/Perl/perl5/issues/13681>.
 
 =item Aliasing via reference
@@ -66,7 +66,7 @@ Introduced in Perl 5.22.0
 Using this feature triggers warnings in the category
 C<experimental::refaliasing>.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #14150]|https://github.com/Perl/perl5/issues/14150>.
 
 See also: L<perlref/Assigning to References>
@@ -78,7 +78,7 @@ Introduced in Perl 5.22.0
 Using this feature triggers warnings in the category
 C<experimental::const_attr>.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #14428]|https://github.com/Perl/perl5/issues/14428>.
 
 See also: L<perlsub/Constant Functions>
@@ -90,11 +90,14 @@ Introduced in Perl 5.22.0
 Using this feature triggers warnings in the category
 C<experimental::re_strict>.
 
+The ticket for this experiment is
+L<[perl #18755]|https://github.com/Perl/perl5/issues/18755>
+
 See L<re/'strict' mode>
 
 =item The <:win32> IO pseudolayer
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #13198]|https://github.com/Perl/perl5/issues/13198>.
 
 See also L<perlrun/PERLIO>
@@ -106,24 +109,28 @@ Introduced in Perl 5.26.0
 Using this feature triggers warnings in the category
 C<experimental::declared_refs>.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #15458]|https://github.com/Perl/perl5/issues/15458>.
 
 See also: L<perlref/Declaring a Reference to a Variable>
 
 =item There is an C<installhtml> target in the Makefile.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #12726]|https://github.com/Perl/perl5/issues/12726>.
 
 =item (Limited) Variable-length look-behind
 
-Introduced in Perl 5.30.0.  Variability of up to 255 characters is
-handled.
+Introduced in Perl 5.30.0.
+
+Variability of up to 255 characters is handled.
 
 Using this feature triggers warnings in the category
 C<experimental::vlb>.
 
+The ticket for this experiment is
+L<[perl #18756]|https://github.com/Perl/perl5/issues/18756>.
+
 See also: L<perlre/(*positive_lookbehind:I<pattern>)> and
 L<perlre/(*negative_lookbehind:I<pattern>)>
 
@@ -134,7 +141,7 @@ Introduced in Perl 5.32.0.
 Using this feature triggers warnings in the category
 C<experimental::isa>.
 
-The ticket for this feature is
+The ticket for this experiment is
 L<[perl #18754]|https://github.com/Perl/perl5/issues/18754>
 
 =back