New version 26.1
    
    - Generate plain text variants of the help content files (mkolman)
    - Add a plain text version of of the placeholder (mkolman)
    - Fix some typos (mkolman)
    - Use /usr/bin/python3 in conversion script header (mkolman)
    - Update help content (mkolman)
    - Fix link to the installation guide git repository (mkolman)