doca - Create an option for schema glob

[rbuckland]

Currently the **/*.json glob for finding schemas is not changeable. (hard coded).

My schema project has the following layout

/schemas/
   /foo/something-special.schema.json
   /foo/something-speacial-sample-data-1.json
   /foo'something-speacial-sample-data-1.json

I need to be able to glob on just **/*.schema.json

for example

doca init -g "**/*.schema.json" -o docs

This is my attempt... https://github.com/rbuckland/json-schema-tools/tree/feature/doca-glob-option