docs: describe current state only, and fill in the stub READMEs

Drop the history and roadmap asides: which services predate the collection's
conventions, the unwired Open Web UI plan, the generic clone-and-troubleshoot
boilerplate. Services that publish ports or set `restart:` now simply say so.

couchbase, openvpn-as and traffmonetizer had two-line READMEs; give them the
ports, variables and storage the root README promises. traffmonetizer reads
${TOKEN} and had no .env.example, so add one.

traffmonetizer/.env.example

@@ -0,0 +1,6 @@
+# Copy to .env and fill in. Never commit .env.
+#
+#   cp .env.example .env
+
+# Application token from the TraffMonetizer dashboard, under "Your token".
+TOKEN=