Customer Action Limitations are in consistent with Custom Action Configuration docs and UI

Issue in ./help/using/about/limitations.md

In the Custom Action Limitations section of this doc it mentions this line:

- Only POST and PUT call methods are supported

However, in the Custom Action Configuration doc, Endpoint configuration section (https://experienceleague.adobe.com/en/docs/journey-optimizer/using/configuration/configure-journeys/action-journeys/about-custom-action-configuration#url-configuration) it clearly states that Post, Put, and GETs are supported. And in the actual product UI, I'm able to select a GET option.

So unless this limitation of POST and PUT refers to something other than the EndPoint configuration, we can remove this limitation, add GET to the list of limitations, or go the opposite and say that we don't support PATCH or DELETE methods.

Start with help/using/about/limitations.md and review the linked Custom Action Configuration endpoint documentation, then compare both with the GET option described in the product UI. Confirm which HTTP methods are supported and update the Custom Action Limitations section so its wording matches the documented and observed behavior.

Written by the indexing model from the issue text.