Update README.md to include information about the API

README.md

 # REST API Examples
 
 This repository provides some examples for interacting with the SNAC REST API.
+
+## Instructions
+
+For testing purposes, please use the REST API located at:
+
+```
+http://snac-dev.iath.virginia.edu:81
+```
+
+When you are ready to "go live" with your project, switch to the production API located at:
+
+```
+http://snac-web.iath.virginia.edu:81
+```
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