Add composer install step and ACF Pro notes

[aslamatwebdevstudios]

Closes

NA

What type of PR is this? (put an x to all applicable)

• [ ] 🍕 Feature
• [ ] 🐛 Bug Fix
• [x] 📝 Documentation Update
• [ ] 🎨 Style
• [ ] 🧑‍💻 Code Refactor
• [ ] 🔥 Performance Improvements
• [ ] ✅ Test
• [ ] 🤖 Build
• [ ] 🔁 CI
• [ ] 📦 Chore (Release)
• [ ] ⏩ Revert

Link to test

Description

• Added step to install composer packages
• Added note to install ACF Pro plugin to use CLI generated blocks

Related Tickets & Documents

Mobile & Desktop Screenshots/Recordings

Added tests?

• [ ] 👍 yes
• [ ] 🙅 no, because they aren't needed
• [ ] 🙋 no, because I need help

Added to documentation?

• [ ] 📜 README.md
• [ ] 📓 Confluence
• [ ] 🙅 no documentation needed

Others

• [ ] 🦮 Is this issue accessible? (Section 508/WCAG 2.0AA)
• [ ] 🙌 Does this issue pass all the linting? (PHPCS, ESLint, SassLint)

[optional] Are there any post-deployment tasks we need to perform?