Update guide/intro to take into account the removal of proc.

cc @steveklabnick

Author: nikomatsakis

reference.md

@@ -187,19 +187,18 @@ grammar as double-quoted strings. Other tokens have exact rules given.
 
 <p id="keyword-table-marker"></p>
 
-|          |          |          |          |        |
-|----------|----------|----------|----------|--------|
-| abstract | alignof  | as       | be       | box    |
-| break    | const    | continue | crate    | do     |
-| else     | enum     | extern   | false    | final  |
-| fn       | for      | if       | impl     | in     |
-| let      | loop     | match    | mod      | move   |
-| mut      | offsetof | once     | override | priv   |
-| proc     | pub      | pure     | ref      | return |
-| sizeof   | static   | self     | struct   | super  |
-| true     | trait    | type     | typeof   | unsafe |
-| unsized  | use      | virtual  | where    | while  |
-| yield    |          |          |          |        |
+|          |          |          |          |         |
+|----------|----------|----------|----------|---------|
+| abstract | alignof  | as       | be       | box     |
+| break    | const    | continue | crate    | do      |
+| else     | enum     | extern   | false    | final   |
+| fn       | for      | if       | impl     | in      |
+| let      | loop     | match    | mod      | move    |
+| mut      | offsetof | once     | override | priv    |
+| pub      | pure     | ref      | return   | sizeof  |
+| static   | self     | struct   | super    | true    |
+| trait    | type     | typeof   | unsafe   | unsized |
+| use      | virtual  | where    | while    | yield   |
 
 
 Each of these keywords has special meaning in its grammar, and all of them are
@@ -3842,8 +3841,6 @@ x = bo(5,7);
 ```{.ebnf .notation}
 closure_type := [ 'unsafe' ] [ '<' lifetime-list '>' ] '|' arg-list '|'
                 [ ':' bound-list ] [ '->' type ]
-procedure_type := 'proc' [ '<' lifetime-list '>' ] '(' arg-list ')'
-                  [ ':' bound-list ] [ '->' type ]
 lifetime-list := lifetime | lifetime ',' lifetime-list
 arg-list := ident ':' type | ident ':' type ',' arg-list
 bound-list := bound | bound '+' bound-list
@@ -3852,8 +3849,6 @@ bound := path | lifetime
 
 The type of a closure mapping an input of type `A` to an output of type `B` is
 `|A| -> B`. A closure with no arguments or return values has type `||`.
-Similarly, a procedure mapping `A` to `B` is `proc(A) -> B` and a no-argument
-and no-return value closure has type `proc()`.
 
 An example of creating and calling a closure:
 
@@ -3876,30 +3871,6 @@ call_closure(closure_no_args, closure_args);
 
 ```
 
-Unlike closures, procedures may only be invoked once, but own their
-environment, and are allowed to move out of their environment. Procedures are
-allocated on the heap (unlike closures). An example of creating and calling a
-procedure:
-
-```rust
-let string = "Hello".to_string();
-
-// Creates a new procedure, passing it to the `spawn` function.
-spawn(proc() {
-  println!("{} world!", string);
-});
-
-// the variable `string` has been moved into the previous procedure, so it is
-// no longer usable.
-
-
-// Create an invoke a procedure. Note that the procedure is *moved* when
-// invoked, so it cannot be invoked again.
-let f = proc(n: int) { n + 22 };
-println!("answer: {}", f(20));
-
-```
-
 ### Object types
 
 Every trait item (see [traits](#traits)) defines a type with the same name as