gen-addon-readme: generate static/description/index.html
gen-addon-readme: generate static/description/index.html

It is exactly the same as README.rst, but useful nevertheless since
apps.odoo.com gives better visibility to addons with an html description.
Manually generated index.html are preserved.

acsone/maintainer-tools,OCA/maintainer-tools,OCA/maintainer-tools,acsone/maintainers-tools,acsone/maintainer-tools,acsone/maintainers-tools,Yajo/maintainer-tools,Yajo/maintainer-tools,OCA/maintainer-tools,acsone/maintainer-tools,OCA/maintainer-tools,acsone/maintainers-tools,acsone/maintainer-tools,Yajo/maintainer-tools,Yajo/maintainer-tools