Document new mint validate CLI command

[hahnbeelee]

Added documentation for the new mint validate command in the installation guide. This command validates documentation builds in strict mode and is designed for CI/CD pipelines to prevent broken documentation from being deployed.

Changes

• Updated installation.mdx to add a new "Validate documentation build" section under "Additional commands"
• Documented available flags: --groups and --disable-openapi
• Added GitHub Actions workflow examples showing how to use the command in CI/CD pipelines

Generated from feat: add new validate-build cli command @rtbarnes

---

Note

Introduces mint validate for strict documentation builds, intended for CI usage.

• Adds Validate documentation build section in installation.mdx with mint validate usage
• Documents flags: --groups [groupname] and --disable-openapi
• Provides GitHub Actions examples using npx mint validate, including group-specific validation

^{Written by Cursor Bugbot for commit 2ef27d4. This will update automatically on new commits. Configure here.}

[tembo]

Minor nit: using <...> for placeholders tends to read clearer than [...] here.

Suggested change

	- `--groups <groupname>`: Mock user groups for validation (useful when testing partial authentication).

[tembo]

In CI, npx can sometimes prompt to install the package; adding --yes prevents hangs.

Suggested change

	```yaml
	run: npx --yes mint validate

[tembo]

Same here to keep the workflow non-interactive.

Suggested change

	```yaml
	run: npx --yes mint validate --groups admin

[ethanpalm]

closing in favor of #2736