Created Collections module (markdown)

Collections-module.md

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+[Official docs ](https://docs.python.org/3/library/collections.html)
+
+* [built-in](https://docs.micropython.org/en/latest/library/collections.html)
+    * deque (fast, very incomplete)
+    * namedtuple
+    * OrderedDict
+* [micropython-lib](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/collections)
+    * [defaultdict](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/collections.defaultdict)
+    * [deque](https://github.com/micropython/micropython-lib/tree/master/python-stdlib/collections.deque) (slow, more complete)
+* Not implemented yet
+    * [ChainMap](https://docs.python.org/3/library/collections.html#collections.ChainMap)
+    * [Counter](https://docs.python.org/3/library/collections.html#collections.Counter)
+    * [UserDict](https://docs.python.org/3/library/collections.html#collections.UserDict)
+    * [UserList](https://docs.python.org/3/library/collections.html#collections.UserList)
+    * [UserString](https://docs.python.org/3/library/collections.html#collections.UserString)