feat: add amz-content-sha256 extension to docs

[felipegenef]

Description

@Telroshan Here My PR related to this previous PR on HTMX Extensions. As we discussed there , I hosted the extension on my repository and added it to the Docs as a Community Extension.

This Pull Request adds a new reference to a community extension that addresses use cases where users interact with AWS services that require the SigV4 integrity header, such as in this example. Several AWS services depend on this header, and I encountered this exact issue in my own open-source project that uses HTMX.

Given that others may experience the same issue, I believe this functionality will be beneficial.

Corresponding issue:

This PR on EXtensions

Testing

I added a Test folder into the repository root following the pattern shown in the official htmx-extensions repository.

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded