docs: Add links to issues referenced in README.rst.
docs: Add links to issues referenced in README.rst.

pimusicbox/mopidy-musicbox-webclient,pimusicbox/mopidy-musicbox-webclient,woutervanwijk/Mopidy-MusicBox-Webclient,pimusicbox/mopidy-musicbox-webclient,woutervanwijk/Mopidy-MusicBox-Webclient,woutervanwijk/Mopidy-MusicBox-Webclient