When importing a repo, the placeholder text (never a good way to convey meaningful information) shows a sample url without the protocol: github.com/my-org/my-repo

However, when trying to enter a repo url matching that example, the UI simply says "Invalid repo URL format" which is frustrating for the user because they're following the example provided

It turns out, users need to add the protocol (https://) and then it will work. As a very early step in onboarding a repo to IDX, this can lead to frustration.

Solution:
1. update placeholder text to include protocol
2. update error message to provide a potential solution, "Make sure protocol is included in URL"