patch 8.2.0578: heredoc for interfaces does not support "trim"
Problem: Heredoc for interfaces does not support "trim".
Solution: Update the script heredoc support to be same as the :let command.
(Yegappan Lakshmanan, closes #5916)
diff --git a/runtime/doc/if_perl.txt b/runtime/doc/if_perl.txt
index f1bf923..b0bad1e 100644
--- a/runtime/doc/if_perl.txt
+++ b/runtime/doc/if_perl.txt
@@ -55,7 +55,7 @@
working: >
:perl VIM::Msg("Hello")
-:pe[rl] << [endmarker]
+:pe[rl] << [trim] [{endmarker}]
{script}
{endmarker}
Execute Perl script {script}.