move gmid to the eight section of the manual

changes for 1.8.4

document the implicit mapping for text/gemini and remove the explicit mapping from the documentation and test files.

document the `types' behavior

add an entry for text/gemini in the `types' example if using `types' the internal listing is not used, so show how to add the entries for text/gemini when using /usr/share/misc/mime.types.


move the documentation of the config file into gmid.conf.5