docs: add watchdocs target, stub pages for fibers/lists/maps, fix class example, and move build output to build/docs

doc/site/classes.markdown

@@ -28,9 +28,10 @@ To make our unicorn do stuff, we need to give it methods.
 This defines a `prance` method that takes no arguments. To support parameters, add a parenthesized parameter list after the method's name:
 
     :::dart
-    // Inside class...
-    prance(where, when) {
-      IO.print("The unicorn prances in " + where + " at " + when)
+    class Unicorn {
+      prance(where, when) {
+        IO.print("The unicorn prances in " + where + " at " + when)
+      }
     }
 
 Unlike most other dynamically-typed languages, in Wren you can have multiple methods in a class with the same name, as long as they take a different number of parameters. In other words, you can overload by arity. So this class is fine:

doc/site/fibers.markdown

@@ -0,0 +1,3 @@
+^title Fibers
+
+**TODO**

doc/site/functions.markdown

@@ -0,0 +1,3 @@
+^title Functions
+
+**TODO**

doc/site/lists.markdown

@@ -0,0 +1,3 @@
+^title Lists
+
+**TODO**

doc/site/maps.markdown

@@ -0,0 +1,3 @@
+^title Maps
+
+**TODO**

doc/site/method-calls.markdown

@@ -83,7 +83,7 @@ it `b`".
 
 Most of these are probably familiar already. The `..` and `...` operators are
 "range" operators. The number type implements those and returns a range object,
-which can in turn be iterated over using a [`for`](loops.html) loop.
+which can in turn be iterated over using a `for` [loop](looping.html).
 
 ## Subscript operators
 

doc/site/template.html

@@ -35,9 +35,9 @@
       <li><a href="values.html">Values</a></li>
       <li><a href="classes.html">Classes</a></li>
       <li><a href="functions.html">Functions</a></li>
-      <li>Fibers</li>
-      <li>Lists</li>
-      <li>Maps</li>
+      <li><a href="fibers.html">Fibers</a></li>
+      <li><a href="lists.html">Lists</a></li>
+      <li><a href="maps.html">Maps</a></li>
     </ul>
     <h2>Usage</h2>
     <ul>

doc/site/values.markdown

@@ -3,9 +3,6 @@
 Values are the built-in object types that all other objects are composed of.
 They can be created through *literals*, expressions that evaluate to a value.
 
-All value types in Wren are immutable. That means that once created, they
-cannot be changed. `3` is always three and `"hi"` is always `"hi"`.
-
 ## Booleans
 
 A boolean value represents truth or falsehood. There are two boolean literals,