Installation, Usage for readme

Author: eduard93

README.md

@@ -1,2 +1,23 @@
 # GitHubAPI
 Github API for InterSystems Caché
+
+## Installation
+
+Import xmls into any namespace and compile.
+
+## Usage
+
+First create api object to interact with GitHub API (provide valid GitHub user and pass):
+
+`Set api = ##class(GitHub.API).%New("user","pass")`
+
+After that you can query some GitHub APIs. For example to get info about all public repos in organization:
+
+`Do api.GetOrgRepos("intersystems-ru","public",.repos)`
+
+All availible API calls are listed in class documentation of `GitHub.API` class.
+
+Some workflows to automate work with GitHub are availible in `GitHub.Workflows` class.
+
+## Some API method I want is not availible. What do I do?
+Everyone is welcome to add methods or wokflows via pull requests.