move installation above usage

Author: Thinh Nguyen

README.md

@@ -6,6 +6,17 @@ There are two modules in `element-animal`:
 
 See [Background](Background.md) for the background information and development timeline.
 
+
+## Installation
+```
+pip install element-animal
+```
+
+If you already have an older version of ***element-animal*** installed using `pip`, upgrade with
+```
+pip install --upgrade element-animal
+```
+
 ## Element usage
 
 + `element-animal` is not a complete workflow by itself, but rather a modular design of tables and dependencies that can be flexibly attached to any DataJoint workflow.
@@ -24,12 +35,3 @@ See [Background](Background.md) for the background information and development t
 ![genotyping diagram](images/genotyping_diagram.svg)
 
 
-## Installation
-```
-pip install element-animal
-```
-
-If you already have an older version of ***element-animal*** installed using `pip`, upgrade with
-```
-pip install --upgrade element-animal
-```