Best Practice: When not to use blank lines

[christianbraeunlich]

Almost copied 1:1 from https://alguidelines.dev/docs/navpatterns/3-cal-coding-guidelines/readability/blank-lines/

NOTE: if https://github.com/microsoft/alguidelines/pull/154 is merged first - create new subfolder blank-lines, a file _index.md and the following content:

---
title: "Blank Lines"
---