adjust references to `md2pdf` as it now resides under github.com/solw…

…orktech

Add anchor for TOC from `Features` section

We want the deb/RPM package name to remain `mdtopdf`, even though the…

… repo name

changed. Hopefully, setting `project_name` will do the trick.

Remove the below from the `Known Issues` section as it was addressed:

4. Currently all levels of unordered lists use a dash for the bullet.
This is a planned fix; [see here](#1).

A more elaborate table test, following #71

Document `--version` option

Rename version variable

(see https://goreleaser.com/cookbooks/using-main.version)

typo

pull submodule

Build debs and RPMs as part of the release process