doc: provider-perl

Enable 'has("perl")' as an alias for 'g:loaded_perl_provider'.

TODO:
- +perl interface

runtime/doc/provider.txt

@@ -126,6 +126,31 @@ To use an absolute path (e.g. to an rbenv installation): >
 To use the RVM "system" Ruby installation: >
     let g:ruby_host_prog = 'rvm system do neovim-ruby-host'
 
+==============================================================================
+Perl integration				*provider-perl*
+
+Nvim supports Perl |remote-plugin|s.
+https://github.com/jacquesg/p5-Neovim-Ext
+
+
+PERL QUICKSTART~
+
+To use perl remote-plugins with Nvim, install the "Neovim::Ext" cpan package: >
+    cpanm -n Neovim::Ext
+
+Run |:checkhealth| to see if your system is up-to-date.
+
+
+PERL PROVIDER CONFIGURATION~
+						*g:loaded_perl_provider*
+To disable Perl support: >
+    :let g:loaded_perl_provider = 0
+<
+						*g:perl_host_prog*
+Command to start the Perl executable. Must be set before any
+check for has("perl").  >
+    let g:perl_host_prog = '/path/to/perl'
+<
 ==============================================================================
 Node.js integration				*provider-nodejs*
 

src/nvim/eval.c

@@ -24611,6 +24611,7 @@ bool eval_has_provider(const char *feat)
       && !strequal(feat, "python_dynamic")
       && !strequal(feat, "python3_compiled")
       && !strequal(feat, "python3_dynamic")
+      && !strequal(feat, "perl")
       && !strequal(feat, "ruby")
       && !strequal(feat, "node")) {
     // Avoid autoload for non-provider has() features.