Add .github/ docs

[maurolepore]

E.g.

# TODO: 
# * Move to .github/
# * EDIT-PACKAGE-NAME
use_template(template = "CODE_OF_CONDUCT.md", package = "fgeo.template")
use_template(template = "CONTRIBUTING.md", package = "fgeo.template")
use_template(template = "ISSUE_TEMPLATE.md", package = "fgeo.template")
use_template(template = "SUPPORT.md", package = "fgeo.template")