Unclear block attribute positions

[pushkine]

The Attributes on block expressions section specifies when inner attributes are allowed in blocks, it's unclear whether that applies to outer attributes too? Even more confusing is that the example showcases outer attributes instead

reference/src/expressions/block-expr.md

Lines 143 to 164 in 411c2f0

	## Attributes on block expressions
	[Inner attributes] are allowed directly after the opening brace of a block expression in the following situations:
	* [Function] and [method] bodies.
	* Loop bodies ([`loop`], [`while`], [`while let`], and [`for`]).
	* Block expressions used as a [statement].
	* Block expressions as elements of [array expressions], [tuple expressions],
	[call expressions], and tuple-style [struct] expressions.
	* A block expression as the tail expression of another block expression.
	<!-- Keep list in sync with expressions.md -->
	The attributes that have meaning on a block expression are [`cfg`] and [the lint check attributes].
	For example, this function returns `true` on unix platforms and `false` on other platforms.
	```rust
	fn is_unix_platform() -> bool {
	#[cfg(unix)] { true }
	#[cfg(not(unix))] { false }
	}
	```

[ehuss]

It seems reasonable to me to add an example of an inner attribute and also a demonstration of where it is invalid (such as a closure?).

Those restrictions are for inner attributes only. Perhaps as a reminder, it could link to https://github.com/rust-lang/reference/blob/411c2f0d5cebf48453ae2d136ad0c5e611d39aec/src/expressions.md#expression-attributes to explain the limitations on outer attributes when used as an expression/statement?