Add documentation in README and in --help

Remove docs dir, since that's not how project documentation seems to be done.

README.md

@@ -375,6 +375,26 @@ $ ./node_modules/.bin/cucumber.js
 
 **Note to Windows users:** invoke Cucumber.js with `cucumber-js` instead of `cucumber.js`. The latter is causing the operating system to invoke JScript instead of Node.js, because of the so-called file extension.
 
+#### Formatters
+
+Use --format to specify the formatter.
+
+``` shell
+$ cucumber.js --format=json
+```
+
+Cucumber.js provides progress (the default), summary, JSON and pretty
+formatters.
+
+You can also specify a custom formatter by providing the path to a file
+implementing the formatter:
+
+``` shell
+$ cucumber.js --format=/path/to/my_formatter.js
+```
+
+Paths should be absolute or relative to the current working directory.
+
 ### Examples
 
 A few example apps are available for you to browse:

lib/cucumber/cli.js

@@ -65,6 +65,7 @@ function Cli(argv) {
                                 json    : prints the feature as JSON\n\
                                 summary : prints a summary only, after all\n\
                                           scenarios were executed\n\
+                                filename: load custom formatter from filename\n\
 \n\
 -i, --no-snippets             Don't print snippets for pending steps.\n\
 \n\