Contact info: Update platforms & methods to contact the Council
    
    This commit updates information about how to contact the Fedora Council
    and the best places to get in touch. This updates information about IRC
    and mailing lists, and replaces them either with platform-agnostic
    language or Matrix/Discourse specifically, where applicable.
    
    This commit builds on what @mattdm already put together in January 2022
    in PR #138. There is not a significant change to what was already voted
    on and decided previously, but I did reorganize some of the content on
    the "Contact" page in an attempt to enhance the page structure already
    laid out. It includes @bcotton's feedback asked for previously.
    
    These changes are a year old and do not include changes to the charter
    other than links to the Council meetings wiki page and changing the
    Discourse link from the old category to the Council tag. I intend to
    merge this on commit, on the conditional affirmation by the Council has
    approved this change during our February 2023 face-to-face meeting in
    Frankfurt, Germany.
    
    ref: Fedora-Council/council-docs#138
    
    Signed-off-by: Justin W. Flory (he/him) <jwf@redhat.com>