runtime(pandoc): refine pandoc compiler settings

closes: #15529

Signed-off-by: Christian Brabandt <cb@256bit.org>
Signed-off-by: Konfekt <Konfekt@users.noreply.github.com>
diff --git a/runtime/doc/quickfix.txt b/runtime/doc/quickfix.txt
index da13b46..e44c5d5 100644
--- a/runtime/doc/quickfix.txt
+++ b/runtime/doc/quickfix.txt
@@ -1,4 +1,4 @@
-*quickfix.txt*  For Vim version 9.1.  Last change: 2024 Aug 05
+*quickfix.txt*  For Vim version 9.1.  Last change: 2024 Aug 20
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1345,6 +1345,13 @@
 - either by appending them to make, say `:make html --self-contained` .
 - or setting them in `b:pandoc_compiler_args` or `g:pandoc_compiler_args`.
 
+The `--from` argument is an educated guess using the buffer file type;
+it can be overridden by setting `b:pandoc_compiler_from`.
+Likewise the `--metadata lang` argument is set using `&spelllang`;
+it can be overridden by setting `b:pandoc_compiler_lang`.
+If `--from=markdown` is assumed and no title set in a title header or
+YAML block, then the filename (without extension) is used as the title.
+
 PERL					*quickfix-perl* *compiler-perl*
 
 The Perl compiler plugin doesn't actually compile, but invokes Perl's internal