Add documentation link in the task details

Description

As a user, I would like to read the documentation of the task from the pipeline builder. Link out to original documentation will help to get more information about the task.

Acceptance Criteria

1. Task details should contain a documentation link, that opens the documentation in a new window.
2. If the hubURL is not present in the API response, the documentation link button should not be shown.

Additional Details:

`hubURL` key to be provided by the tektonhub API response. Here is the link to the Hub PR

Note: The UI work will be done as part of API contract provided by the hub team (refer the above PR for field name), so by the time of completion of the UI work, we may or may not have the API in-place for QE verification. The QE Verification cannot be done if the API is not available by the end of development sprint.