Add development instructions to readme.

Author: hperrin

README.md

@@ -10,6 +10,37 @@ I made this app because I would often not notice my chat messages on my other mo
 
 Head over to the [releases page](https://github.com/hperrin/stream-overlay/releases) to download the latest version.
 
+## Development
+
+After checking out the repo, run the following in the repo's folder.
+
+```sh
+npm install
+cd app/app
+npm install
+cd ../..
+npm start
+```
+
+Under most circumstances, it's easiest to just Ctrl+C that instance and run `npm start` again, instead of running watchers.
+
+When you've completed your changes and are ready to package it up, run the following.
+
+```sh
+npm run clean
+npm run build
+npm run package:windows # or package:linux
+```
+
+And if you want to build the flatpak and install it locally (on Linux), run the following after the above commands.
+
+```sh
+git submodule init
+git submodule update
+npm run flatpak:generate-manifest
+npm run package:flatpak
+```
+
 ## Support Me
 
 You can support me directly by supporting my software company, SciActive, on Patreon:

package.json

@@ -14,7 +14,7 @@
     "format": "prettier --write --plugin-search-dir=. .",
     "package:linux": "electron-builder build --x64 --linux",
     "package:windows": "electron-builder build --x64 --win",
-    "package:flatpak": "npm run flatpak:generate-manifest && flatpak-builder build flatpak/com.hperrin.StreamOverlay.yml --install --force-clean --user",
+    "package:flatpak": "flatpak-builder build flatpak/com.hperrin.StreamOverlay.yml --install --force-clean --user",
     "flatpak:generate-manifest": "python3 flatpak-builder-tools/node/flatpak-node-generator.py npm -r -o flatpak/generated-sources.json --xdg-layout app/package-lock.json",
     "test": "echo \"Error: no test specified\" && exit 1",
     "postinstall": "electron-builder install-app-deps"