Merge pull request #1763 from joshtriplett/use-cfg-false

Use `cfg(false)` instead of `cfg(FALSE)`

Author: ehuss

src/items/enumerations.md

@@ -345,7 +345,7 @@ macro_rules! mac_variant {
 mac_variant! { E }
 
 // This is allowed, since it is removed before being validated.
-#[cfg(FALSE)]
+#[cfg(false)]
 enum E {
     pub U,
     pub(crate) T(u8),

src/tokens.md

@@ -612,7 +612,7 @@ Note that `-1i8`, for example, is analyzed as two tokens: `-` followed by `1i8`.
 Examples of integer literals which are not accepted as literal expressions:
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(false)] {
 0invalidSuffix;
 123AFB43;
 0b010a;
@@ -697,7 +697,7 @@ Note that `-1.0`, for example, is analyzed as two tokens: `-` followed by `1.0`.
 Examples of floating-point literals which are not accepted as literal expressions:
 
 ```rust
-# #[cfg(FALSE)] {
+# #[cfg(false)] {
 2.0f80;
 2e5f80;
 2e5e6;