Update README.md

Author: UziTech

README.md

@@ -1 +1,58 @@
-# atom-ide-code-format
+# Code Format
+
+Format a selection of code using the `code-format:format-code` command.  
+(Also accessible via context menu, or "Edit > Text > Format Code").
+
+When no selection is provided, the entire file is formatted.
+
+![Code Format](./images/code-format.gif)
+
+Code Format also provides APIs to:
+
+- format code as you type
+- format code on save (after you press save but before writing to disk).
+
+You can enable format-on-save using plain range/file providers from the
+"atom-ide-code-format" section in the `atom-ide-ui` package settings.
+
+## Service API
+
+Provide code format [Atom services](http://flight-manual.atom.io/behind-atom/sections/interacting-with-other-packages-via-services/) by adding one or more of these to your `package.json`:  
+(Only the ones that you want to use; you don't need all of them!)
+
+```
+"providedServices": {
+  "code-format.range": {
+    "versions": {
+      "0.1.0": "provideRangeCodeFormat"
+    }
+  },
+  "code-format.file": {
+    "versions": {
+      "0.1.0": "provideFileCodeFormat"
+    }
+  },
+  "code-format.onType": {
+    "versions": {
+      "0.1.0": "provideOnTypeCodeFormat"
+    }
+  },
+  "code-format.onSave": {
+    "versions": {
+      "0.1.0": "provideOnSaveCodeFormat"
+    }
+  }
+}
+```
+
+Then, in your package entry point:
+
+```
+export function provideRangeCodeFormat(): RangeCodeFormatProvider {}
+export function provideFileCodeFormat(): FileCodeFormatProvider {}
+export function provideOnTypeCodeFormat(): OnTypeCodeFormatProvider {}
+export function provideOnSaveCodeFormat(): OnSaveCodeFormatProvider {}
+```
+
+The various provider types are described in
+[`atom-ide-code-format/lib/types.js`](../modules/atom-ide-ui/pkg/atom-ide-code-format/lib/types.js).