Register 12 new JSON filenames/extensions

[Alhadis]

These were pilfered from the extensions list of Atom's JSON grammar.

• .avsc
  • Usage: ~17,637 results
  • Sample source: redjack/rflow-components-http
  • Sample license: Apache 2.0
• .gltf
  • Usage: ~34,389 results
  • Sample source: BabylonJS/Website
  • Sample license: Apache 2.0
• .htmlhintrc
  • Usage: ~5,319 results
  • Sample source: webgefrickel/webgefrickel.de
  • Sample license: MIT
• .jscsrc
  • Usage: ~612,450 results
  • Sample source: kswedberg/jquery-smooth-scroll
  • Sample license: MIT
• .jslintrc
  • Usage: ~5,111 results
  • Notes: Added as JSON5 because the format supports JS comments, which aren't valid JSON (and will cop glaring red error highlighting).
  • Sample source: mroderick/PubSubJS
  • Sample license: MIT
• .jsonl
  • Usage: ~8,264 results
  • Notes: Not to be confused with JSONLD. Refers to JSON Lines, a newline-delimited variant of JSON.
  • Sample source: kubernetes/kubernetes
  • Sample license: Apache 2.0
• .tern-config
  • Usage: ~909 results / 709 repos / 695 users
  • Sample source: galeo/dotfiles
  • Sample license: MIT
• .tern-project
  • Usage: ~247,529 results
  • Sample source: agrc/ugs-chemistry
  • Sample license: MIT
• .tfstate
  • Usage: ~4,675 results
  • Sample source: hashicorp/terraform
  • Sample license: MPL 2.0
• .tfstate.backup
  • Usage: ~1,802 results
  • Sample source: NickHeiner/fitbit-export
  • Sample license: MIT
• .webapp
  • Usage: ~43,159 results
  • Sample source: darkoverlordofdata/demo-cocos2d-tsc
  • Sample license: MIT
• .webmanifest
  • Usage: ~5,668 results
  • Sample source: martincostello/credit-card-splitter
  • Sample license: Apache 2.0

[lildude]

LGTM