readme update

Add fixable for readme and update docs to reflect additional argument

Author: snowypowers

README.md

@@ -117,7 +117,7 @@ Finally, enable all of the rules that you would like to use.  Use [our preset](#
 * [react/jsx-curly-spacing](docs/rules/jsx-curly-spacing.md): Enforce or disallow spaces inside of curly braces in JSX attributes (fixable)
 * [react/jsx-equals-spacing](docs/rules/jsx-equals-spacing.md): Enforce or disallow spaces around equal signs in JSX attributes (fixable)
 * [react/jsx-filename-extension](docs/rules/jsx-filename-extension.md): Restrict file extensions that may contain JSX
-* [react/jsx-first-prop-new-line](docs/rules/jsx-first-prop-new-line.md): Enforce position of the first prop in JSX
+* [react/jsx-first-prop-new-line](docs/rules/jsx-first-prop-new-line.md): Enforce position of the first prop in JSX (fixable)
 * [react/jsx-handler-names](docs/rules/jsx-handler-names.md): Enforce event handler naming conventions in JSX
 * [react/jsx-indent](docs/rules/jsx-indent.md): Validate JSX indentation
 * [react/jsx-indent-props](docs/rules/jsx-indent-props.md): Validate props indentation in JSX (fixable)

docs/rules/jsx-first-prop-new-line.md

@@ -2,6 +2,8 @@
 
 Ensure correct position of the first property.
 
+**Fixable:** This rule is automatically fixable using the `--fix` flag on the command line.
+
 ## Rule Details
 
 This rule checks whether the first property of all JSX elements is correctly placed. There are three possible configurations:
@@ -10,6 +12,12 @@ This rule checks whether the first property of all JSX elements is correctly pla
 * `multiline`: The first property should always be placed on a new line when the JSX tag takes up multiple lines.
 * `multiline-multiprop`: The first property should always be placed on a new line if the JSX tag takes up multiple lines and there are multiple properties.
 
+In order to utilise autofix, please specify the indentation style as an additional argument in your configuration:
+
+```json
+"jsx-first-prop-new-line": ["always", 2]
+```
+
 The following patterns are considered warnings when configured `"always"`:
 
 ```jsx