Update `texinfo_updateSectionMenu.sh':
- Don't use the MANUAL_CHAPTER_DIR variable here. Use `$(dirname
${MANUAL_ENTRY})' instead; it is safer.
The MANUAL_CHAPTER_DIR variable, here, is used as base location
to reach the `chapter-menu.texinfo' definition file. When no
chapter name is provided to `centos-art.sh' script as non-option
parameter in the command-line, the value of MANUAL_CHAPTER_DIR
will be empty as well and path to `chapter-menu.texinfo' file
will be wrong.
The `$(dirname ${MANUAL_ENTRY})' construction, on the other
hand, will always return the chapter directory where the section
entry is stored in. No matter if the chapter information wasn't
provided to `centos-art.sh' script in the command-line.
- Be sure menu entries won't be duplicated when new menu entries
are added/updated.