stop automatic git commits of schema-reference.md

[jrcheli]

resolves #997

[michalbiesek]

@jrcheli Looks good to me.

I allowed myself to add one commit. This is not strictly related to your change. Let me describe what I have added:

• During the schema markdown generation process we start by resolving references "$ref": e.g.

  "properties": {
    "type": {
      "$ref": "definitions/envelope.schema.json#/$defs/event_type"
    },

This is done by json-dereference.
If "$ref" is invalid e.g. points to no existing definition we will retrieve the syntax error like e.g. following:

SyntaxError: Error resolving $ref pointer "/home/node/schemas/definitions/envelope.schema.json#/$defs/event_type3". 

But the json-dereference will still return 0 - just like in the case of success. I have added an additional logic to check if the file with resolved references was generated. If a file with fixed references was not generated, exit 1 will fail the job.

After merging this Pull Request we should check if the new Github Action is working correctly even with a simple change in a single JSON schema file.

[michalbiesek]

@jrcheli Not sure if it is worthy or not - since I am not aware of the exact process of how deploy works.
Should we extend the .gitignore file with the following entry:

/website/src/pages/docs/schema-reference.md

My rationale is to prevent situation including the /website/src/pages/docs/schema-reference.md file in the commit ?