Merge pull request #8 from RaspberryPiFoundation/seb-testing-locally-instructions

**docs: document alternative approach for local development**

Whilst recently attempting to test some changes to the webpack config we struggled to get npm link to work.

We ended up using an alternative approach using npm pack which generates a tarball of the npm package which you can then npm install into your other project.

In order to help future developers who find themselves in a similar situation I thought it was worth documenting this alternative approach.

Author: sebjacobs

README.md

@@ -43,8 +43,7 @@ Then go to [http://localhost:8601/](http://localhost:8601/) - the playground out
 
 ## Developing alongside other Scratch repositories
 
-### Getting another repo to point to this code
-
+### Getting another repo to point to this code (using `npm link`)
 
 If you wish to develop `scratch-gui` alongside other scratch repositories that depend on it, you may wish
 to have the other repositories use your local `scratch-gui` build instead of fetching the current production
@@ -82,6 +81,31 @@ If you can't get linking to work right, try:
   repositories, make sure to use the same node version in all of them.
 * If nothing else works, unlink the repositories by running `npm unlink` in both, and start over.
 
+##### Getting another repo to point to this code (using `npm pack`)
+
+If you struggle to get npm link working then this alternative approach might be for you.
+
+1. Make your code changes to the scratch-gui code.
+2. Rebuild the scratch-gui project:
+
+```
+BUILD_MODE=dist npm run build
+```
+
+3. Build the scratch-gui npm package locally (this will create a gzipped tarball e.g ScratchFoundation-scratch-gui-4.1.0-beta.1.tgz).
+
+```
+npm pack
+```
+
+4. npm install and rebuild your other project (using the gzipped tarball):
+
+```
+cd ../other-project
+npm install ../scratch-gui/RaspberryPiFoundation-scratch-gui-4.1.0-beta.1.tgz --force
+npm run build
+```
+
 ## Testing
 
 ### Documentation