Updated README to add TFS info and added tags (#239)

Author: damccorm

README.md

@@ -97,6 +97,8 @@ run();
 
 To see what APIs are available, see the appropriate client interface. For example, [GitApi.ts](https://github.com/Microsoft/azure-devops-node-api/blob/master/api/GitApi.ts)
 
+More detailed information for the endpoints of each API can be found at https://docs.microsoft.com/en-us/rest/api/vsts/?view=vsts-rest-4.1
+
 ## Running Samples
 
 Pre-reqs: [Node >= 4.4.7 LTS](https://nodejs.org) and [typescript (tsc) >= 1.8](https://www.npmjs.com/package/typescript)  
@@ -126,6 +128,18 @@ Run a specific sample:
 $ npm run samples -- http
 ```
 
+## API and TFS Mapping
+
+Below you'll find a quick mapping of azure-devops-node-api versions and their corresponding TFS releases. All API versions will work on the server version mentioned as well as later versions.
+
+ |**TFS Version** | **Node API VERSION**|
+ |-------------------|------------------|
+ |TFS 2018 Update 2  |  6.6.2|
+ |TFS 2017 Update 2  |  6.2.8-preview|
+ |TFS 2017 Update 1  |  5.1.2|
+ |TFS 2017 RTW       |  5.0.0|
+ |TFS 2015 Update 2  |  0.7.0|
+
 ## Contributing
 
 To contribute to this repository, see the [contribution guide](./CONTRIBUTING.md)