Update request_for_changes.md to add link to dashboard

Summary

This Merge Request adds a link to all dashboard builds for the Merge Request. The user has to specify the branch name for the url when using the template.

See bellow how it looks like:

Dashboard status

Direct link to all dashboard builds related to this Merge Request

(This is an example with 1506-refactor-MapProjectionAdapter, but will also work with randomized build ids from new CI).

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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Check before merging:

• All discussions are resolved
• At least 2 votes from core developers, no vote.
• The feature branch is (reasonably) up-to-date with the base branch
• Dashboard is green
• Copyright owner has signed the ORFEO ToolBox Contributor License Agreement