ox-texinfo:: Require only TEXINFO_DIR_CATEGORY

Until now @dircategory/@direntry entries were added only if
both TEXINFO_DIR_CATEGORY and TEXINFO_DIR_TITLE were set.
And the setting of TEXINFO_DIR_TITLE had to be careful to
provide exactly the right syntax.

This patch changes various things in this regard:
- Only require TEXINFO_DIR_CATEGORY in order to generate
  `@dircategory` and `@direntry`.
- Use the document title by default if TEXINFO_DIR_DESC is missing.
- Use the filename by default when TEXINFO_DIR_TITLE is missing.
- Try and make it harder to provide a direntry that does not
  have the right format or refers to a different filename than
  the one we're outputting to.

* lisp/org/ox-texinfo.el: Remove redundant `:group` arguments.
Prefer #' to quote function names.
(org-texinfo-template): Use sane defaults for `@direntry`.

* doc/misc/org.org (Texinfo specific export settings): Adjust accordingly.

1 files changed, 9 insertions, 2 deletions

diff --git a/doc/misc/org.org b/doc/misc/org.org
index 05ab5b36ca0..f4590525892 100644
--- a/doc/misc/org.org
+++ b/doc/misc/org.org
@@ -15322,11 +15322,18 @@ the general options (see [[*Export Settings]]).
 
   #+cindex: @samp{TEXINFO_DIR_TITLE}, keyword
   The directory title of the document.
+  This is the short name under which the ~m~ command will find your
+  manual in the main Info directory.  It defaults to the base name of
+  the Texinfo file.
+
+  If you need more control, it can also be the full entry using the
+  syntax ~* TITLE: (FILENAME).~.
 
 - =TEXINFO_DIR_DESC= ::
 
   #+cindex: @samp{TEXINFO_DIR_DESC}, keyword
   The directory description of the document.
+  Defaults to the title of the document.
 
 - =TEXINFO_PRINTED_TITLE= ::
 
@@ -15422,7 +15429,7 @@ Here is an example that writes to the Info directory file:
 
 #+begin_example
 ,#+TEXINFO_DIR_CATEGORY: Emacs
-,#+TEXINFO_DIR_TITLE: Org Mode: (org)
+,#+TEXINFO_DIR_TITLE: Org Mode
 ,#+TEXINFO_DIR_DESC: Outline-based notes management and organizer
 #+end_example
 
@@ -15830,7 +15837,7 @@ Texinfo code.
 ,#+TEXINFO_HEADER: @syncodeindex pg cp
 
 ,#+TEXINFO_DIR_CATEGORY: Texinfo documentation system
-,#+TEXINFO_DIR_TITLE: sample: (sample)
+,#+TEXINFO_DIR_TITLE: sample
 ,#+TEXINFO_DIR_DESC: Invoking sample
 
 ,#+TEXINFO_PRINTED_TITLE: GNU Sample