docs: section headings as uppercase

[profanis]

Following a conversation with @arturovt, I'm opening a pull request to update the section headings. I've converted them all to uppercase.

[nx-cloud]

☁️ Nx Cloud Report

CI is running/has finished running commands for commit b786bc2. As they complete they will appear below. Click to see the status, the terminal output, and the build insights.

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✅ Successfully ran 4 targets

• nx run-many --target=test --all --configuration=ci --maxWorkers=4
• nx run-many --target=lint --all
• nx lint-types store
• nx run-many --target=build --all

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Sent with 💌 from NxCloud.

[bundlemon]

BundleMon (Integration Projects)

Unchanged files (2)

Status	Path	Size	Limits
✅	Main bundles(Gzip) hello-world-ng17/dist-integration/main.(hash) .js	68.49KB	+1%
✅	Main bundles(Gzip) hello-world-ng16/dist-integration/main.(hash) .js	67.03KB	+1%

No change in files bundle size

Final result: ✅

View report in BundleMon website ➡️

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Current branch size history | Target branch size history

[codeclimate]

Code Climate has analyzed commit b786bc2 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 95.2% (0.0% change).

View more on Code Climate.

[arturovt]

looks amazing!