[7.6] Generate haproxy module docs (#16776)

[ycombinator]

Backports the following commits to 7.6:

• Generate haproxy module docs (Generate haproxy module docs #16776)

[dedemorton]

I don't think this is required. When you run make update or mage fmt update on the other PR you have open, this file will get updated automatically.

[kaiyan-sheng]

Error: some files are not up-to-date. Run 'mage fmt update' then review and commit the changes. Modified: [metricbeat/docs/modules/haproxy.asciidoc
Seems like mage fmt update is needed.

[ycombinator]

Closing PR. Changes will be incorporated into #16801.

[ycombinator]

Closing PR. Changes will be incorporated into #16801.