Fill in some more basic syntax docs.

doc/site/syntax.markdown

@@ -2,6 +2,11 @@
 
 Wren's syntax is designed to be familiar to people coming from C-like languages while being as simple and expressive as possible within that framework.
 
+Scripts are stored in plain text files with a `.wren` file extension. Wren does
+not compile ahead of time: programs are run directly from source, from top to
+bottom like a typical scripting language. (Internally, programs are compiled to
+bytecode for efficiency, but that's an implementation detail).
+
 ## Comments
 
 Line comments start with `//` and end at the end of the line:
@@ -9,45 +14,55 @@ Line comments start with `//` and end at the end of the line:
     :::wren
     // This is a comment.
 
-Block comments start with `/*` and end with `*/`. They can span multiple lines or be within a single one. Unlike C, block comments can nest in Wren:
+Block comments start with `/*` and end with `*/`. They can span multiple lines
+or be within a single one. Unlike C, block comments can nest in Wren:
 
     :::wren
     /* This is /* a nested */ comment. */
 
-## Literals
+## Reserved Words
 
-Wren currently supports a few atomic types: booleans, numbers, strings, and the null type. Numbers are double-precision floating point values, and strings are text. Wren doesn't support a lot of fancy formats for them yet, just the basic:
+Some people like to see all of the reserved words in a programming language in
+one lump. If you're one of those folks, here you go:
 
     :::wren
-    0
+    class else false fn for if is null
-    1234
+    return static this true var while
-    -432.1
-    "a string"
-    "another string"
-    "supported escapes: \" \n \\"
 
-Wren also has a couple of special values:
+## Newlines
 
-* `null` indicates the absence of a value.
+Like many scripting languages, newlines are significant in Wren and are used to
-* `this` inside a method refers to the method's receiver.
+separate statements. You can keep your semicolons safely tucked away.
-* `true` and `false` are boolean values.
-
-## Variables
-
-Variables are named references to values. Naming rules mostly follow C. They start with a letter and can contain letters, digits, and underscores (`_`). Some examples:
 
     :::wren
-    foo
+    // Two statements:
-    Bar
+    io.write("hi")
-    bestFriends4eva
+    io.write("bye")
-    under_score
 
-Variables can be declared using `var`:
+Sometimes, though, you want to wrap a single statement on multiple lines. To
+make that easier, Wren has a very simple rule. It will ignore a newline
+following any token that can't end a statement. Specifically, that means any of
+these:
 
     :::wren
-    var pie = "pumpkin"
+    ( [ { . , * / % + - | || & && ! ~ = < > <= >= == !=
+    class else if is static var while
 
-**TODO: Scoping**
+Everywhere else, a newline is treated just like a `;`.
+
+## Names
+
+Identifiers are similar to other programming languages. They start with a letter or underscore and may contain letters, digits, and underscores. Case is sensitive.
+
+    :::wren
+    hi
+    camelCase
+    PascalCase
+    _under_score
+    abc123
+    ALL_CAPS
+
+Identifiers that start with underscore (`_`) are special in Wren. They are used to indicate fields and private members of classes.
 
 ## Method calls