mail-templates: Update for Fedora Linux instead of Fedora, spellings
    
    Main change:
    
    Fedora is a community; Fedora Linux is our OS.
    https://communityblog.fedoraproject.org/fedora-is-a-community-fedora-linux-is-our-os/
    
    Thus we should use "Fedora Linux N" instead of "Fedora N".
    
    Additional changes:
    
    - use YYYY-MM-DD for all date values.
      Exception: 05-beta-release uses "end of MONTH".
    
    - use fN as the designator for the Fedora Linux release number.
      Note: Many URLs are now f-fN, which needs to be replaced to f-37
    
    - Add a space before inline cross references.
      This was inconsistent: sometimes [1] and sometimes[2].
    
    - References start with [1] and not with [0]
    
    - Fix two instances of incorrect capitalization
      ("fedora repository" instead of "Fedora repository" and
      "fedora Project wiki" instead of "Fedora Project wiki").
    
    - Except for lines with URL, linit line length to 72 characters.
    
    Signed-off-by: Manfred Spraul <manfred@colorfullife.com>