Added basic building instructions

README.md

@@ -1,4 +1,26 @@
 # Furbooru Tagging Assistant
 
 This is a browser extension written for the [Furbooru](https://furbooru.org) image-board. It gives you the ability to
-tag the images more easily and quickly.
+tag the images more easily and quickly.
+
+## Building
+
+Recommendations on environment:
+
+- Recommended version of Node.js: LTS (20)
+
+First you need to clone the repository and install all packages:
+
+```shell
+npm install --save-dev
+```
+
+Second, you need to run the `build` command. It will first build the popup using SvelteKit and then build all the 
+content scripts/stylesheets and copy the manifest afterward. Simply run:
+
+```shell
+npm run build
+```
+
+When building is complete, resulting files can be found in the `/build` directory. These files can be either used 
+directly in Chrome (via loading the extension as unpacked extension) or manually compressed into `*.zip` file.