runtime(doc): add package-<name> helptags for included packages

Improve how to find the justify package

closes: #16420

Co-authored-by: Peter Benjamin <petermbenjamin@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/usr_02.txt b/runtime/doc/usr_02.txt
index 70d24d3..a02835d 100644
--- a/runtime/doc/usr_02.txt
+++ b/runtime/doc/usr_02.txt
@@ -1,4 +1,4 @@
-*usr_02.txt*	For Vim version 9.1.  Last change: 2024 Oct 05
+*usr_02.txt*	For Vim version 9.1.  Last change: 2025 Jan 11
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -694,6 +694,13 @@
 	:help E128
 <    takes you to the |:function| command
 
+27) Documenction for packages distributed with Vim have the form package-<name>.
+     So >
+	:help package-comment
+<
+    will bring you to the help section for the included comment plugin and how to
+    enable it.
+
 
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