Add local testing and linking guide

CONTRIBUTING.md

@@ -31,6 +31,27 @@ Please try to use the original style in the codebase. Do not introduce new rules
 Nue is not using Prettier or ESLint because they will increase the project size to 40MB. The `.prettierrc.csj` file on the root directory does the job well enough.
 
 
-
-
-
+### Testing
+
+```sh
+# if using bun
+bun install
+bun test
+# if using node
+npm install
+npm install --global jest
+node --experimental-vm-modules $(which jest)
+```
+
+
+### Linking
+
+```sh
+# node only
+npm install
+cd packages/nuekit
+npm link
+cd create-nue/simple-crm
+node $(which nue)
+node $(which nue) build --production
+```