Adds changelog, update contributing

Author: tomnomnom

CHANGELOG.mkd

@@ -0,0 +1,9 @@
+# Changelog
+
+## 0.1.1
+- Adds support for fetching URLs directly
+
+## 0.1.0
+- Support for files
+- Support for `stdin`
+

CONTRIBUTING.mkd

@@ -7,3 +7,18 @@
 * Make sure the tests pass (run `./script/test`)
 * Make sure the linters pass (run `./script/lint`)
 * Issue a pull request
+
+## Commit Messages
+I'd prefer it if commit messages describe what the *commit does*, not what *you did*.
+
+For example, I'd prefer:
+
+```
+Adds lint; removes fluff
+```
+
+Over:
+
+```
+Added lint; removed fluff
+```

README.mkd

@@ -64,7 +64,7 @@ The output of `gron` is valid JavaScript:
   name: 'Tom' }
 ```
 
-Get help:
+## Get Help
 
 ```
 ▶ gron --help