chore: shared raedme update

Author: sonofmagic

packages/shared/README.md

@@ -2,6 +2,22 @@
 
 The shared utils of tailwindcss-mangle
 
+## Install
+
+```bash
+<npm|yarn|pnpm> i tailwindcss-mangle-shared
+```
+
 ## Usage
 
-// TODO
+### ClassGenerator
+
+the class generator of tailwindcss-mangle
+
+### escapeStringRegexp
+
+### makeRegex
+
+### splitCode
+
+### defaultMangleClassFilter