deps.edn workflow & support

[RickMoynihan]

Add notes to docs about how to consume from the new clj tool and deps.edn, e.g.

:aliases {  :table2qb {:extra-deps {
                        {:git/url "https://github.com/Swirrl/table2qb/"
                         :sha "some-sha-here"}}
           :main-opts ["-m" "table2qb.main"
                               "exec" "cube-pipeline"
                               "--column-config" "foo/bar/components.csv"
                              ,,,,]}}

Then we can run at the commandline like so:

$ clojure -A:table2qb blah blah

Which will be handy in some projects, as it will mean some of our projects can just include a snippet in their deps.edn file and expose the tool to project users, without them having to fetch and install the jar etc.

Could also look at making this a deps.edn project (for :git/url support).

[Robsteranium]

This is a great suggestion and a nifty little way of using the library.

The description provided by the above patch looks good for the most part but it doesn't actually work. It seems like you can't include a :tag without a :sha - indeed the :tag is optional and seems only to be descriptive - which strikes me as a bit of a poor design as you can specify a sha that has nothing to do with the tag! Perhaps it's supposed to be a generic tag, not a git tag. In any case I suggest we identify a sha in the snippet (so that it works) and potentially add a comment with the tag/ release number etc.