Educate users in the "create topic" and "create topic collection" modals

As an author in Joplin, I want to know how to write titles for topic collections and topics that connect residents to what they're looking for. I also want to learn more about the IA when I create these containers, so I know how to organize my content in an easily navigable, searchable way.

**Is your feature request related to a problem? Please describe.**
Right now the "create topic" and "create topic collection" modals in Joplin don't convey the fact that you're changing and/or adding to the IA when you create them. Instructions aren't accurate, as we're deciding the IA-in-progress.

**Describe the solution you'd like**
We'll want to make sure the welcome mat to creating these content types is accurate when admins can access it.

One way to serve this need is to link from the modals to a resource on doing keyword research, as well as the style guide.

**Describe alternatives you've considered**
We'll also want to think about role-specific content within Joplin, the style guide, and training. To be super succinct in the modal, we could also surface this TBD part of the style guide once you draft the page, because you can always edit it.

**Additional context**