[CIVIS-1775] MAINT update civis_api_spec.json

[jacksonlee-civis]

This PR updates civis_api_spec.json, moves it to under civis/resources/, and checks in a script for maintainers to facilitate updating it again.

Closes #157

• (For Civis employees only) Reference to a relevant ticket in the pull request title
• Changelog entry added to CHANGELOG.md at the repo's root level
• Description of change in the pull request description
• If applicable, unit tests have been added and/or updated
• The CircleCI builds have all passed

[jacksonlee-civis]

Practically, BASE_RESOURCES_V1 is now a reference list of the publicly available API endpoints, used only by the Sphinx docs to auto-generate the API resources documentation (see docs/source/conf.py). As I've just updated civis_api_spec.json, this list now looks like the following:

In [1]: from civis.resources._resources import BASE_RESOURCES_V1

In [2]: BASE_RESOURCES_V1
Out[2]: 
['admin',
 'aliases',
 'announcements',
 'clusters',
 'credentials',
 'databases',
 'endpoints',
 'enhancements',
 'exports',
 'feature_flags',
 'files',
 'git_repos',
 'groups',
 'imports',
 'jobs',
 'json_values',
 'match_targets',
 'media',
 'models',
 'notebooks',
 'notifications',
 'ontology',
 'permission_sets',
 'predictions',
 'projects',
 'queries',
 'remote_hosts',
 'reports',
 'roles',
 'saml_service_providers',
 'scripts',
 'search',
 'services',
 'storage_hosts',
 'table_tags',
 'tables',
 'templates',
 'users',
 'workflows']

[madopal]

LGTM, assuming some successful runs to produce new docs.