cleanup docs #1

ucloud/docs/source/introduction/howitworks.rst

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+How does ucloud work?
+=====================
+
+ucloud is separeted into 3 systems:
+
+1. The client side for using ucloud
+2. The server side
+3. The supporting infrastructure (databases, virtualisation, etc.)
+
+
+Depending on your use case, select one of the following guides to
+continue:
+
+* I want to use
+* I want to operate/run ucloud as a service
+
+
+Architecture
+------------
+Description of the ucloud architecture