Added incomplete getting-started text

doc/basics.md

@@ -1,2 +1,16 @@
-TBC
+### Creating a new Mutex
+
+A new mutex, an instance of type `Mutex[ValueType]` for some choice of
+`ValueTyp`, can be constructed by supplying its initial value to the `Mutex`
+factory method, like so:
+```scala
+val count: Mutex[Int] = Mutex(32)
+```
+
+This represents a mutex variable, which is set to `32`. Any thread which has a
+reference to `count` may read or modify this variable, but only in delimited
+blocks.
+
+We can read the value only through a lambda applied to the `read` method of
+`Mutex`, which provides a reference for accessing the value.