refactor: revamp whole Emacs.org

This is the first part of consolidating my Emacs and NixOS config
into a single file. This commit refactors the whole of Emacs.org
and adds more bits of prose to the configuration sections.

programs/git/.gitmessage

@@ -0,0 +1,10 @@
+
+#                         max. 50 chars is here: #
+# <type>[optional scope]: <description>
+# types: feat, fix, build, chore, ci, docs, style, refactor, perf, test
+# ! indicates a breaking change.
+
+
+# Body:                                      wrap at 72 chars is here: #
+# Include at least one empty line before co-authored. Format:
+# Co-authored-by: name <user@users.noreply.github.com>