limit formatOnSave option to JS/TS files, add docs re: prettier

docs/in-depth/prettier.md

@@ -0,0 +1,19 @@
+# Prettier
+
+[Prettier](https://prettier.io/) is an automatic code formatter which supports various languages, including TypeScript. It also has extensions for various text editors like [VSCode](https://github.com/prettier/prettier-vscode), [Atom](https://github.com/prettier/prettier-atom), and even [Vim](https://github.com/prettier/vim-prettier). If you have installed these extensions, it will use Prettier's service to automatically format your code after saving.
+
+If you would rather not use Prettier instead, you can easily disable it too. In VSCode, open `.vscode/settings.json`, then change the `"editor.formatOnSave"` option to `false`:
+
+```json
+{
+  "[json]": {
+    "editor.formatOnSave": false
+  },
+  "[javascript]": {
+    "editor.formatOnSave": false
+  },
+  "[typescript]": {
+    "editor.formatOnSave": false
+  }
+}
+```

docs/in-depth/typescript.md

@@ -33,10 +33,10 @@ This project provides TSLint rules through a `tslint.json` file, which extends t
 
 We've made some changes to these rules, which we considered necessary and/or relevant to a proper Screeps project:
 
- - set the [forin](http://palantir.github.io/tslint/rules/forin/) rule to `false`, it was forcing `for ( ... in ...)` loops to check if object members were not coming from the class prototype.
- - set the [interface-name](http://palantir.github.io/tslint/rules/interface-name/) rule to `false`, in order to allow interfaces that are not prefixed with `I`.
- - set the [no-console](http://palantir.github.io/tslint/rules/no-console/) rule to `false`, in order to allow using `console`.
- - in the [variable-name](http://palantir.github.io/tslint/rules/variable-name/) rule, added `allow-leading-underscore`.
+* set the [forin](http://palantir.github.io/tslint/rules/forin/) rule to `false`, it was forcing `for ( ... in ...)` loops to check if object members were not coming from the class prototype.
+* set the [interface-name](http://palantir.github.io/tslint/rules/interface-name/) rule to `false`, in order to allow interfaces that are not prefixed with `I`.
+* set the [no-console](http://palantir.github.io/tslint/rules/no-console/) rule to `false`, in order to allow using `console`.
+* in the [variable-name](http://palantir.github.io/tslint/rules/variable-name/) rule, added `allow-leading-underscore`.
 
 ### Customising TSLint