Improve setup instructions and README

- README cleanups and link to documentation
- Improve dev setup instructions
- Fix js linting errors
- Move local setup instructions to installation docs
- Project link fix, closes #42
- Notes about frontend
- Clarify different LND backends

package.json

@@ -1,5 +1,8 @@
 {
   "devDependencies": {
     "prettier": "^2.0.5"
+  },
+  "scripts": {
+    "lint": "prettier --write lnbits/static/js/** lnbits/core/static/js/** lnbits/extensions/*/templates/**"
   }
 }