CLI, debian, make: misc cleanup and changes (#336)

This PR	groups misc cleanup and changes from https://github.com/ooni/probe-cli/pull/331.

* CLI/linux/build: add documentation

* debian/.gitignore: ignore generated files

* debian/TODO: unnecessary at this point

* debian/ooniprobe-cli.service: remove commented out lines

* debian/rules: remove unnecessary actions

* make: reindent and fix spelling

* smoketest.sh: don't run in verbose mode

Part of https://github.com/ooni/probe/issues/1466

debian/.gitignore

@@ -0,0 +1,7 @@
+/bin
+/.debhelper/
+/debhelper-build-stamp
+/files
+/ooniprobe-cli/
+/ooniprobe-cli.postrm.debhelper
+/ooniprobe-cli.substvars