runtime(doc): cross-link :| meaning :p and explain E749

E749 is given when :print (with any range) is issued on an empty buffer,
like the one you get with :new or :enew. Furthermore, due to Vi
compatibility :| is a synonym.

As a result, mappings intended to include a <bar> separator (esp. in the
case of boolean or "||") between commands can generate E749 on startup
when placed in a vimrc if the bars are not properly encoded or escaped.
[1]. Document this failure mode and synonym near the generated error,
and cross link with :help :bar. Note that one must read or scroll quite
a bit to find the mention of :| behaving like :print!

[1]: https://vi.stackexchange.com/q/46625/10604

closes: #17173

Signed-off-by: D. Ben Knoble <ben.knoble+github@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index 6fd4a5f..b68c336 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -1,4 +1,4 @@
-*various.txt*   For Vim version 9.1.  Last change: 2025 Feb 13
+*various.txt*   For Vim version 9.1.  Last change: 2025 Apr 21
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -98,7 +98,9 @@
 
 						*:p* *:pr* *:print* *E749*
 :[range]p[rint] [flags]
-			Print [range] lines (default current line).
+			Print [range] lines (default current line).  Can also
+			be spelled `:[range]|` due to Vi compatibility (see
+			|:bar|).  Gives an error in an empty buffer.
 			Note: If you are looking for a way to print your text
 			on paper see |:hardcopy|.  In the GUI you can use the
 			File.Print menu entry.