Fix links that point to the old solps-doc url #1

Figure out what the RTD url will be... probably https://solps-wiki.readthedocs.io/ but maybe there's some subpath? Hopefully we can disable that.

Then use search & replace across all files to replace the old https://solps.pages.tok.ipp.cas.cz/solps-doc/ with the new RTD url.

Pay special attention to mkdocs config in mkdocs.yml, there is the site_url variable and custom link to B2 input viewer in the nav that needs to work correctly.