Avoid displaying duplicative "Type / to choose a block" prompts

[kean]

What problem does this address?

What is your proposed solution?

• Remove the "Type / to choose a block" prompt, as it's a rarely used feature on mobile (tracks needed)
• Add a one-time tip to teach the user about the "/"
• Consider showing tips only when you connect a hardware keyboard
• (Alternative) show "Type / to choose a block" only for the very first empty paragraph block in an empty post