added yarn + added yarn2 install script

yarn2.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env sh
+dir=$(pwd)
+
+# shellcheck disable=SC2129
+printf "\n" >> "$dir/.gitignore"
+printf "\n###Yarn 2" >> "$dir/.gitignore"
+printf "\n.yarn/*" >> "$dir/.gitignore"
+printf "\n!.yarn/releases" >> "$dir/.gitignore"
+printf "\n!.yarn/plugins" >> "$dir/.gitignore"
+
+# Upgrade Yarn to Berry (latest Yarn 2 version known to Yarn 1)
+yarn set version berry
+
+# Upgrade Yarn Berry to latest version now that Yarn knows where to download it from
+yarn set version latest
+
+# (optional) Set nodeLinker to node-modules - this 100% guarantees backwards compatibility
+yarn config set nodeLinker node-modules
+
+# (optional) Adds `yarn upgrade-interactive` command back
+yarn plugin import interactive-tools
+
+# Reinstalls project using Yarn 2. This will also update your yarn.lock file, but will NOT sneakily upgrade the dependencies
+yarn