docs: Add troubleshooting tips to migrating vue components

What does this MR do?

After working with some members of the design team to migrate vue button components to GlButton, we determined that some troubleshooting tips would helpful. This MRs add the tips.

Does this MR meet the acceptance criteria?

Conformity

• [-] Code review guidelines.
• GitLab UI's contributing guidlines.
• [-] If it changes a Pajamas-compliant component's look & feel, the MR has been reviewed by a UX designer.
• If it changes GitLab UI's documentation guidelines, the MR has been reviewed by a Technical Writer.
• [-] If the MR changes a component's API, integration MR(s) have been opened in the following projects to ensure that the @gitlab/ui package can be upgraded quickly after the changes are released:
  • GitLab: mr_url
  • Customers Portal: mr_url
  • Status Page: mr_url
• [-] Added the ~"component:*" label(s) if applicable.