Automate Conversion of examples.toml into examples.json

[bitner]

With updates to the playground, we've added an examples.toml file where we can add examples with both a cql2_text and cql2_json version and also add a name and description describing each example.

We can use the rust lq command line tool to convert this into the 'docs/examples.json' file that is used to populate the select in the playground.

We should automate the conversion and placement of that file.