docs: added README.md to the client (#57)

Author: chuckjaz

client/R67RcGftRS.gif

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+# Angular Language Service
+
+![demo](R67RcGftRS.gif)
+
+## Using
+
+This extension provides a rich editing experience for Angular templates, both inline
+and external templates including:
+
+* Completions lists
+* AOT Diagnostic messages
+* Quick info
+* Go to definition
+
+This extension uses `@angular/language-service@4.1.0-beta` and `typescript@2.1.5`.