Update documentation for lambda_manager role

[robotdan]

Doc:

• https://fusionauth.io/docs/get-started/core-concepts/roles

This indicates that lambda_manager can only add and edit lambdas, but because we do not ship a lambda_deleter role, this role can also delete lambda functions.

The doc should be update to provide clarity.

Internal:

• https://tracker.bugcrowd.com/fusionauth/submissions/f77eb339-7a7f-4a0e-a6a1-13d7294aa531

[mooreds]

Related: #3448

Looks like there are a few others that need this change as well.

[robotdan]

Perhaps - this issue isn't so much to add new roles - although we may want to do that - at the time that was an intentional decision.

This issue is primarily to review the doc to ensure it matches reality.

[mooreds]

This should be covered by this PR: #3448 where I audited all the manager roles.