feat: add keyboard keys rendering

Summary

• chore: render keyboard keys
• feat: add keyboard keys rendering

See:

• https://facelessuser.github.io/pymdown-extensions/extensions/keys/
• https://squidfunk.github.io/mkdocs-material/reference/formatting/#adding-keyboard-keys

---

• Close nothing
• Cherry-pick to: none
• Staging:
  • https://docs.binary.picodata.io/picodata/asabirov_add_keyboard_keys/tutorial/connecting/#special_commands
  • https://docs.binary.picodata.io/picodata/asabirov_add_keyboard_keys/tutorial/run/#secure_stop