Added 'Upgrading/downgrading Yarn' to ToC

Ted Stoychev · web-flow · commit 1705b4a65836 · 2019-10-14T17:17:56.000+03:00
diff --git a/docs/BestPractices.md b/docs/BestPractices.md
@@ -4,6 +4,7 @@
 
 - [Environment Variables](#environment-variables)
 - [Global npm dependencies](#global-npm-dependencies)
+- [Upgrading/downgrading Yarn](#upgradingdowngrading-yarn)
 - [Handling Kernel Signals](#handling-kernel-signals)
 - [Non-root User](#non-root-user)
 - [Memory](#memory)
