docs: add inspecting injector section in devtools

[sasidharansd]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] The commit message follows our guidelines: https://github.com/angular/angular/blob/main/CONTRIBUTING.md#commit
• [ ] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [x] Documentation content changes
• [ ] angular.io application / infrastructure changes
• [ ] Other... Please describe:

What is the current behavior?

Inspecting injector section is missing

Fixes #55759

What is the new behavior?

inspecting injector section is added to devtools docs

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

[github-actions[bot]]

Deployed adev-preview for 75b8ec60a95d5a38c3e26908c79e7775eaae2a3d to: https://ng-dev-previews-fw--pr-angular-angular-55764-adev-prev-km50zncx.web.app

Note: As new commits are pushed to this pull request, this link is updated after the preview is rebuilt.

[atscott]

This PR was merged into the repository by commit 8dd5c735c68adac9bfba9496a9efd6bbb09b1d06.

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