Description for default roles

Problem to solve

[FE] Show default role detail in drawer (#456280 - closed) will provide a link to documentation for default roles from member page.

When viewing details on default role, participants noted that it be helpful to lay out a concise description instead of viewing the table linked in documentation.

Proposal

Add concise description for default roles to be added to member detail drawer, update docs to reflect description:

Default Role	Description
Guest	The Guest role is for users who need visibility into a project or group but should not have the ability to make changes, such as external stakeholders.
Reporter	The Reporter role is suitable for team members who need to stay informed about a project or group but do not actively contribute code.
Developer	The Developer role strikes a balance between giving users the necessary access to contribute code while restricting sensitive administrative actions.
Maintainer	The Maintainer role is primarily used for managing code reviews, approvals, and administrative settings for projects. This role can also manage project memberships.
Owner	The Owner role is normally assigned to the individual or team responsible for managing and maintaining the group or creating the project. This role has the highest level of administrative control, and can manage all aspects of the group or project, including managing other Owners.
Minimal Access	The Minimal Access role is for users who need the least amount of access into groups and projects. You can assign this role as a default, before giving a user another role with more permissions.

Once descriptions above are finalized, update the drawer detail for default roles with description: