Improve doc on coq project file

... following the discussion in github on 32fea19d1bb66593e469b1a8e6ad38f3ae1714bf

1 files changed, 8 insertions, 1 deletions

diff --git a/doc/ProofGeneral.texi b/doc/ProofGeneral.texi
index be29a660..40c0ef87 100644
--- a/doc/ProofGeneral.texi
+++ b/doc/ProofGeneral.texi
@@ -4396,12 +4396,19 @@ one project you can set the option as local file variable,
 @ref{Using file variables}. This can be done either directly in
 every file or once for all files of a directory tree with a
 @code{.dir-local.el} file, @inforef{Directory Variables, ,emacs}.
-For this case, this file should contain
+The file @code{.dir-local.el} should then contain
 
 @lisp
 ((coq-mode . ((coq-project-filename . "myprojectfile"))))
 @end lisp
 
+Note that variables set in @code{.dir-local.el} are automatically
+made buffer local (such that files in different directories can
+have their independent setting of @code{coq-project-filename}).
+If you make complex customizations using @code{eval} in
+@code{.dir-local.el}, you might want to add appropriate calls to
+@code{make-local-variable}.
+
 Documentation of the user option @code{coq-project-filename}:
 
 @c TEXI DOCSTRING MAGIC: coq-project-filename