README.md in jekyll-maps-2.0.0 vs README.md in jekyll-maps-2.0.1

@@ -26,10 +26,22 @@
     - jekyll-maps
   ```
 
 ## Usage
 
+### Configure Google API Key
+
+To be able to use Google Maps you need to obtain [API Key](https://developers.google.com/maps/documentation/javascript/get-api-key).
+
+Once you have your API Key you need to add it to Jekyll's `_config.yml`:
+
+  ```yml
+  maps:
+    google:
+      api_key: <YOUR_KEY>
+  ```
+
 ### Data Source
 
 First, add location information to your posts YAML front-matter:
 
   ```yml
@@ -52,28 +64,48 @@
     location:
       latitude: 40.4378698
       longitude: -3.8196204
   ```
   
-When you have your data ready, just add following tag to the page where you want to see the map:
+By default this plugin will display location from the page it's placed on:
 
   ```
   {% google_map %}
   ```
   
+But you can use src attribute to load locations from other places, like posts, collections or data files!
+
+For example, this map will show locations from all posts from 2016:
+  
+  ```
+  {% google_map src="_posts/2016" %}
+  ```
+  
+This map will show locations from a collection called 'my_collection':
+
+  ```
+  {% google_map src="_collections/my_collection" %}
+  ```
+  
+This map will show locations from all data files located in 'my_points' sub-folder:
+
+  ```
+  {% google_map src="_data/my_points" %}
+  ```
+
 You can configure map's dimensions and assign custom CSS class to the element:
 
   ```
-  {% google_map width:100% height:400 class:my-map %}
+  {% google_map width="100%" height="400" class="my-map" %}
   ```
   
 ### Filters
 
 You can also filter which locations to display on the map!<br/>
 For instance, following tag will only display locations from documents which have `lang: en` in their front-matter data.
 
   ```
-  {% google_map lang:en %}
+  {% google_map src="_posts" lang="en" %}
   ```
 
 ### Marker Cluster
 
 By default [Marker Clusterer](https://github.com/googlemaps/js-marker-clusterer) is enabled.