Add Local Network Access (#2096)

Close #1953, adding the suggested spec to the list.

### Changes to `index.json`
This update would trigger the following changes in `index.json`:

<details><summary>Add spec (1)</summary>

```json
{
  "url": "https://wicg.github.io/local-network-access/",
  "seriesComposition": "full",
  "shortname": "local-network-access",
  "series": {
    "shortname": "local-network-access",
    "currentSpecification": "local-network-access",
    "title": "Local Network Access",
    "shortTitle": "Local Network Access",
    "nightlyUrl": "https://wicg.github.io/local-network-access/"
  },
  "organization": "W3C",
  "groups": [
    {
      "name": "Web Platform Incubator Community Group",
      "url": "https://www.w3.org/community/wicg/"
    }
  ],
  "nightly": {
    "url": "https://wicg.github.io/local-network-access/",
    "status": "Draft Community Group Report",
    "alternateUrls": [],
    "repository": "https://github.com/WICG/local-network-access",
    "sourcePath": "index.bs",
    "filename": "index.html"
  },
  "title": "Local Network Access",
  "source": "spec",
  "shortTitle": "Local Network Access",
  "categories": [
    "browser"
  ],
  "standing": "good",
  "tests": {
    "repository": "https://github.com/web-platform-tests/wpt",
    "testPaths": [
      "fetch/local-network-access"
    ]
  }
}
```
</details>

### Tests
These changes look good! 😎

Co-authored-by: browser-specs-bot <>

Author: browser-specs-bot

specs.json

@@ -788,6 +788,7 @@
   "https://wicg.github.io/keyboard-map/",
   "https://wicg.github.io/layout-instability/",
   "https://wicg.github.io/local-font-access/",
+  "https://wicg.github.io/local-network-access/",
   "https://wicg.github.io/manifest-incubations/",
   "https://wicg.github.io/media-feeds/",
   {