doc function updates and additions (#387)

doc/source/netscript/basicfunctions/renamePurchasedServer.rst

@@ -0,0 +1,22 @@
+renamePurchasedServer() Netscript Function
+===================================
+
+.. js:function:: renamePurchasedServer(hostname, newName)
+
+    :RAM cost: 2 GB
+    :param string hostname: Hostname of the purchased server.
+    :param string newName: New name for the given server.
+    :returns: ``true`` if the renaming was succesful.
+
+    Upgrades the purchased server with the specified hostname to have specified amount of RAM.
+
+    The ``hostname`` argument can be any data type, but it will be converted to
+    a string and have whitespace removed. New RAM amount has to be higher than the current RAM
+    and a power of 2. Upgrading a server costs the difference of old RAM server cost and new RAM
+    server cost.
+
+    Example:
+
+    .. code-block:: javascript
+
+        ns.renamePurchasedServer("server", "old_server");