Add note to length method

[gramian]

• Various fixes to SQL filtering (Section 8.1)
• Add note to SQL length method (Section 8.4)
• Add var num arguments to append method (Section 8.4)
• Add @this and @size to reserved identifiers (Section 11.5)

[netlify[bot]]

✅ Deploy Preview for laughing-saha-bb44e9 ready!

Name	Link
🔨 Latest commit	da1b28135648a04da628666742f303267f3e3909
🔍 Latest deploy log	https://app.netlify.com/sites/laughing-saha-bb44e9/deploys/660daeffc74e7b0008026f29
😎 Deploy Preview	https://deploy-preview-254--laughing-saha-bb44e9.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[lvca]

👏

[lvca]

Thanks!