Tweak README (#2)

Author: di

README.md

@@ -1,14 +1,14 @@
 Cannonical source for classifiers on [PyPI](https://pypi.org).
 
-# Usage
+## Usage
 This package's API is two importable objects:
 
-## Classifiers (`trove_classifiers.classifiers`)
+### Classifiers (`trove_classifiers.classifiers`)
 A `set` containing classifiers (as strings). Useful for determining membership
 
 Example - determine if a classifier is valid:
 
-```
+```python
 >>> from trove_classifiers import classifiers
 >>> 'License :: OSI Approved' in classifiers
 True
@@ -17,13 +17,13 @@ False
 >>>
 ```
 
-## Deprecated classifiers (`trove_classifiers.deprecated_classifiers`)
+### Deprecated classifiers (`trove_classifiers.deprecated_classifiers`)
 A `dict`, mapping a deprecated classifier (string) to a list of classifiers
 which replaces it (strings).
 
 Example - determine if a classifier is deprecated:
 
-```
+```python
 >>> from trove_classifiers import deprecated_classifiers
 >>> 'License :: OSI Approved' in deprecated_classifiers
 False