gh: issue templates: Maintainershp section in ext-source

Add a maintainership section in the ext-source template, forcing future
contributors to identify one or more maintainers.

Signed-off-by: Carles Cufi <[email protected]>

Author: carlescufi

.github/ISSUE_TEMPLATE/ext-source.md

@@ -22,6 +22,12 @@ Describe whether you'd like to integrate this external component in the main tre
 or as a module, and why. If the mode of integration is a module, suggest a
 repository name for the module
 
+## Maintainership
+
+List the person(s) that will be maintaing the integration of this external code
+for the foreseeable future. Please use GitHub IDs to identify them. You can
+choose to identify a single maintainer only or add collaborators as well
+
 ## Pull Request
 
 Pull request (if any) with the actual implementation of the integration, be it