Simplify README Homey publish flow

[jelledelaender]

The README publishing section currently presents npx homey app version as a main release step. The preferred simple flow is to run npx homey app publish, let the Homey CLI prompt for version/release notes as needed, then move the draft to Test and submit for certification in Homey Developer Tools.

Update README.md so the release flow matches the actual workflow and keeps npx homey app version out of the main instructions unless it is intentionally added later as an advanced optional note.

[jelledelaender]

Implementation is ready for review in PR #28:

• PR: Simplify Homey publishing docs #28
• Commit: bb1aa9c (Simplify Homey publishing docs codingmammoth/SoundTouchBridge#27)

What changed:

• README now centers the release flow on npx homey app publish.
• Removed npx homey app version from the main publishing instructions.
• Documented that the Homey CLI prompts for version/changelog details when needed, uploads a build, and then Homey Developer Tools is used to publish a Test version and submit for certification.

Verification performed:

• git diff --check
• npm test
• npx homey app validate

Homey validation passed at publish level; the CLI printed the known non-fatal local update-check warning for /Users/jelle/.config.