mcb-ZH-257 - Add GH issue template for content suggestions

[M-casado]

Summary

Added a new GitHub issue template for content change requests, made for non-technical users that are not familiar with GH but can contribute with their requests to the repository.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New content (non-breaking change which adds new content)
• [ ] Modified content (non-breaking change which modifies existing content)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Motivation and Context

It's needed in order for non-technical users to be able to also contribute to GitHub with their requests.

References

ZenHub #257

Changes Introduced

• Added GH issue template content_suggestion.yaml

Review

Not reviewed yet.

Checklist:

General Compliance:

• [x] My changes follow the code style of this project (GDI SOP Style Guide) and the file naming conventions of the file accessioning proposal.
• [x] I have verified that all new updated content is accessible, including checking that all external references are readable (i.e., no broken links). These may include references to external resources that should be resolvable, and internal references among SOPs.

Only applicable if the PR includes new, or changes to, GDI SOPs (i.e., documents at sops/):

• [ ] My SOP-related changes adhere to the Generic SOP Template, including format and required fields.
• [ ] I have consulted the Charter, ISM, and ORR documents to ensure compliance.
• [ ] I am complying with the established procedure for SOP creations and modifications, including respecting review phases and notifying needed contributors for reviews.

[bhendriksze]

A valuable addition for the process. No review comments.