Document this and that.

Author: mostlyobvious

README.md

@@ -3,6 +3,32 @@
 Content source from git repository. A way to have your writing in public and open for edition while not being distracted 
 by static site generator trivia this content is usually mixed with.
 
+## Usage
+
+Add to `Gemfile` in your nanoc project:
+
+```ruby
+gem "nanoc-github"
+```
+
+Then tell nanoc to load it in `lib/default.rb`:
+
+```ruby
+require "nanoc/github"
+```
+
+At last, enable github data source in `nanoc.yaml`:
+
+```yaml
+data_sources:
+  - type: github
+    items_root: /posts                             # the root where items should be mounted
+    repository: arkency/posts-from-arkency-blog    # organization/repository on github to use as a source of content
+    encoding: utf-8                                # how to decode content                                            (default: utf-8)
+    access_token: secret123                        # github access token, not required for public repositories        (default: nil)
+    path: posts/                                   # subdirectory of the content in given repository                  (default: nil)
+    concurrency: 10                                # how many threads to spawn to fetch data                          (default: 5)
+```
 
 ## Status