Can't specify tags with -a

[rgaudin]

zimwriterfs usage is:

Usage: zimwriterfs [mandatory arguments] [optional arguments] HTML_DIRECTORY ZIM_FILE

Purpose:
	Packing all files (HTML/JS/CSS/JPEG/WEBM/...) belonging to a directory in a ZIM file.

Mandatory arguments:
	-w, --welcome		path of default/main HTML page. The path must be relative to HTML_DIRECTORY.
	-I, --illustration	path of ZIM file illustration. The path must be relative to HTML_DIRECTORY and the image a 48x48 PNG.
	-l, --language		language code of the content in ISO639-3
	-t, --title		title of the ZIM file
	-d, --description	short description of the content
	-L, --longDescription	long description of the content
	-c, --creator		creator(s) of the content
	-p, --publisher		creator of the ZIM file itself

	HTML_DIRECTORY		path of the directory containing the HTML pages you want to put in the ZIM file.
	ZIM_FILE		path of the ZIM file you want to obtain.

Optional arguments:
	-v, --verbose		print processing details on STDOUT
	-h, --help		print this help
	-V, --version		print the version number
	-m, --clusterSize	number of bytes per ZIM cluster (default: 2048Kb)
	-J, --threads		count of threads to utilize (default: 4)
	-x, --inflateHtml	try to inflate HTML files before packing (*.html, *.htm, ...)
	-r, --redirects		path to a TSV file containing a list of redirects (url title target_url).
	-j, --withoutFTIndex	don't create and add a fulltext index of the content to the ZIM.
	-a, --tags		tags - semicolon separated
	-e, --source		content source URL
	-n, --name		custom (version independent) identifier for the content
	-o, --flavour		custom (version independent) content flavour
	-s, --scraper		name & version of tool used to produce HTML content
	--skip-libmagic-check	Accept to run even if magic file cannot be loaded (mimetypes in the zim file may be wrong).

Example:
	zimwriterfs --welcome=index.html --illustration=illustration.png --language=fra --title=foobar --description=mydescription \
		--creator=Wikipedia --publisher=Kiwix ./my_project_html_directory my_project.zim

Documentation:
	zimwriterfs source code: https://github.com/openzim/zim-tools
	ZIM format: https://openzim.org

When using -a TAG, zimwriterfs complains:

zimwriterfs: invalid option -- 'a'

When replacing -a with --tags, it works.