Update document for milestone v1.2.0

[kaibocai]

Once the we release version V1.1.0, we need to udpate documents for below features:

• Suspend and Resume client APIs. Implement suspend and resume client APIs #104. Document
• Add waitForCompletionOrCreateCheckStatusResponse client API. Implement waitForCompletionOrCreateCheckStatusResponse #115. Document
• Restart client API Support restartInstance and add restartPostUri in HttpManagementPayload #125. Document
• Update document for waitForCompletionOrCreateCheckStatusResponse Implement waitForCompletionOrCreateCheckStatusResponse #115 at Document

[kamperiadis]

We also need to update the documentation for the restart client API #125. Document