docs: add CODE_OF_CONDUCT (#3037)

Author: snitin315

CODE_OF_CONDUCT.md

@@ -0,0 +1,7 @@
+## Code of Conduct
+
+At webpack and webpack/webpack-cli repository we follow the [JSFoundation Code of Conduct][1].
+Please adhere to the guidelines there and feel free to report any violation of them to the **@webpack/core-team**,
+**@webpack/dev-server-team**, or <[email protected]>.
+
+[1]: https://github.com/openjs-foundation/code-and-learn/blob/main/CODE_OF_CONDUCT.md