Cardano Updates

This commit updates the use cases section, improving grammar and making the language more appropriate for documentation.

GHC's test suite requires `perl` (e.g. the testsuite driver and various
test scripts). Like `which`, `perl` is not part of stdenv's initialPath
and was only reachable via the host system before the hermetic PATH
change. Add it explicitly to all four shell definitions.

GHC's test suite requires `perl` (e.g. the testsuite driver and various
test scripts). Like `which`, `perl` is not part of stdenv's initialPath
and was only reachable via the host system before the hermetic PATH
change. Add it explicitly to all four shell definitions.

* mithril-cardano-node-chain from `0.1.20` to `0.1.21`

nix: set LANG=C.UTF-8 in shell hook for tests

docs: update nix section with one-liner commands

- Add docker-image package that can be built with nix build .#docker-image
- Uses dockerTools.buildImage to create a minimal container with cardano-address

Even more docs and deploy fixes

GHC's Makefile unconditionally calls `tput bold` and `tput sgr0`
(lines 217-218) which fail with "No value for $TERM and no -T
specified" when TERM is unset. This happens in CI runners and
containers where no terminal is attached.

Set TERM to "dumb" as a fallback after sourcing setup.sh so ncurses
tools like tput degrade gracefully instead of erroring.

- Add formal specs to resources since we'll remove them from the navigation
- Some formatting and editing

GHC's test suite requires `perl` (e.g. the testsuite driver and various
test scripts). Like `which`, `perl` is not part of stdenv's initialPath
and was only reachable via the host system before the hermetic PATH
change. Add it explicitly to all four shell definitions.