docs: Fix errors and typos in public documentation

- Fix `--private-key-file` to `--private-key` in `github-actions.mdx`
  DNS authentication example (the CLI expects hex-encoded key data, not
  a file path)
- Add missing `./` prefix to `mcp-publisher` command in PAT
  authentication example
- Fix typo `verfication` to `verification` in troubleshooting table
- Remove duplicate word `authentication` in `quickstart.mdx`
  prerequisites
- Fix `name` to `identifier` field in JSON examples in `versioning.mdx`
- Fix `PyPi` to `PyPI` (correct capitalization) in
  `moderation-policy.mdx`

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/modelcontextprotocol-io/versioning.mdx

@@ -77,7 +77,7 @@ For local servers, align the server version with the underlying package version
   "packages": [
     {
       "registryType": "npm",
-      "name": "@my-username/my-server",
+      "identifier": "@my-username/my-server",
       "version": "1.2.3",
       "transport": {
         "type": "stdio"
@@ -139,7 +139,7 @@ If you anticipate publishing a server multiple times _without_ changing the unde
   "packages": [
     {
       "registryType": "npm",
-      "name": "@my-username/my-server",
+      "identifier": "@my-username/my-server",
       "version": "1.2.3",
       "transport": {
         "type": "stdio"