Revise proc_macro text

Author: traviscross

src/procedural-macros.md

@@ -85,10 +85,10 @@ r[macro.proc.proc_macro]
 ## The `proc_macro` attribute
 
 r[macro.proc.proc_macro.intro]
-The *`proc_macro` [attribute][attributes]* defines a procedural macro for [function-like macros][macro.invocation].
+The *`proc_macro` [attribute][attributes]* defines a [function-like][macro.invocation] procedural macro.
 
 > [!EXAMPLE]
-> The following macro definition ignores its input and outputs a function `answer` into its scope.
+> This macro definition ignores its input and emits a function `answer` into its scope.
 >
 > <!-- ignore: test doesn't support proc-macro -->
 > ```rust,ignore
@@ -102,7 +102,7 @@ The *`proc_macro` [attribute][attributes]* defines a procedural macro for [funct
 > }
 > ```
 >
-> And then we use it in a binary crate to print "42" to standard output.
+> We can use it in a binary crate to print "42" to standard output.
 >
 > <!-- ignore: requires external crates -->
 > ```rust,ignore
@@ -120,7 +120,7 @@ r[macro.proc.proc_macro.syntax]
 The `proc_macro` attribute uses the [MetaWord] syntax.
 
 r[macro.proc.proc_macro.allowed-positions]
-The `proc_macro` attribute may only be applied to a function with the signature of `pub fn(TokenStream) -> TokenStream` where [`TokenStream`] comes from the [`proc_macro` crate]. It must have the ["Rust" ABI][items.fn.extern]. No other function qualifiers are allowed.
+The `proc_macro` attribute may only be applied to a `pub` function of type `fn(TokenStream) -> TokenStream` where [`TokenStream`] comes from the [`proc_macro` crate]. It must have the ["Rust" ABI][items.fn.extern]. No other function qualifiers are allowed. It must be located in the root of the crate.
 
 r[macro.proc.proc_macro.duplicates]
 The `proc_macro` attribute may only be specified once on a function.
@@ -129,18 +129,18 @@ r[macro.proc.proc_macro.namespace]
 The `proc_macro` attribute publicly defines the macro in the [macro namespace] in the root of the crate with the same name as the function.
 
 r[macro.proc.proc_macro.behavior]
-A function-like macro invocation of a function-like procedural macro will pass what is inside the delimiters of the macro invocation as the input [`TokenStream`] argument, and replace the entire macro invocation with the output [`TokenStream`] of the function.
+A function-like macro invocation of a function-like procedural macro will pass what is inside the delimiters of the macro invocation as the input [`TokenStream`] argument and replace the entire macro invocation with the output [`TokenStream`] of the function.
 
 r[macro.proc.proc_macro.invocation]
 Function-like procedural macros may be invoked in any macro invocation position, which includes:
 
-- [statements]
-- [expressions]
-- [patterns]
-- [type expressions]
-- [item] positions, including items in [`extern` blocks]
-- inherent and trait [implementations]
-- [trait definitions]
+- [Statements]
+- [Expressions]
+- [Patterns]
+- [Type expressions]
+- [Item] positions, including items in [`extern` blocks]
+- Inherent and trait [implementations]
+- [Trait definitions]
 
 <!-- template:attributes -->
 r[macro.proc.derive]