[feat] Support header

[nam-hle]

For #109, #80

• [x] Write tests
• [x] Update docs

Also, restructure the files in /test/README directory to align with the documentation. -> should do in another PR.

[coveralls]

Pull Request Test Coverage Report for Build 362

• 73 of 73 (100.0%) changed or added relevant lines in 13 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 360:	0.0%
Covered Lines:	419
Relevant Lines:	419

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💛 - Coveralls

[gajus]

@nam-hle Made you a collaborator.

Thank you for your contributions.

[nam-hle]

Many thanks!! ☺️☺️☺️

[gajus]

:tada: This PR is included in version 6.7.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: