docs: replace placeholder TODO with full Random module docs and rename parameters from min/max to start/end

doc/site/modules/random/random.markdown

@@ -1,7 +1,95 @@
 ^title Random Class
 
-**TODO**
+A simple, fast pseudo-random number generator. Internally, it uses the [well
+equidistributed long-period linear PRNG][well] (WELL512a).
+
+[well]: https://en.wikipedia.org/wiki/Well_equidistributed_long-period_linear
+
+Each instance of the class generates a sequence of randomly distributed numbers
+based on the internal state of the object. The state is initialized from a
+*seed*. Two instances with the same seed generate the exact same sequence of
+numbers.
+
+
+It must be imported from the [random][] module:
+
+    :::wren
+    import "random" for Random
+
+[random]: ../
+
+## Constructors
+
+### Random.**new**()
+
+Creates a new generator whose state is seeded based on the current time.
+
+    :::wren
+    var random = Random.new()
+
+### Random.**new**(seed)
+
+Creates a new generator initialized with [seed]. The seed can either be a
+number, or a non-empty sequence of numbers. If the sequnce has more than 16
+elements, only the first 16 are used. If it has fewer, the elements are cycled
+to generate 16 seed values.
+
+    :::wren
+    Random.new(12345)
+    Random.new("appleseed".codePoints)
 
 ## Methods
 
-**TODO**
+### **float**()
+
+Returns a floating point value between 0.0 and 1.0, including 0.0, but excluding
+1.0.
+
+    :::wren
+    var random = Random.new(12345)
+    System.print(random.float()) //> 0.53178795980617
+    System.print(random.float()) //> 0.20180515043262
+    System.print(random.float()) //> 0.43371948658705
+
+### **float**(end)
+
+Returns a floating point value between 0.0 and `end`, including 0.0 but
+excluding `end`.
+
+    :::wren
+    var random = Random.new(12345)
+    System.print(random.float(0))     //> 0
+    System.print(random.float(100))   //> 20.180515043262
+    System.print(random.float(-100))  //> -43.371948658705
+
+### **float**(start, end)
+
+Returns a floating point value between `start` and `end`, including `start` but
+excluding `end`.
+
+    :::wren
+    var random = Random.new(12345)
+    System.print(random.float(3, 4))    //> 3.5317879598062
+    System.print(random.float(-10, 10)) //> -5.9638969913476
+    System.print(random.float(-4, 2))   //> -1.3976830804777
+
+### **int**(end)
+
+Returns an integer between 0 and `end`, including 0 but excluding `end`.
+
+    :::wren
+    var random = Random.new(12345)
+    System.print(random.int(1))    //> 0
+    System.print(random.int(10))   //> 2
+    System.print(random.int(-50))  //> -22
+
+### **int**(start, end)
+
+Returns an integer between `start` and `end`, including `start` but excluding
+`end`.
+
+    :::wren
+    var random = Random.new(12345)
+    System.print(random.int(3, 4))    //> 3
+    System.print(random.int(-10, 10)) //> -6
+    System.print(random.int(-4, 2))   //> -2