Fix mistakes on function coroutines related definitions (GH-9871)

Fix a bug I introduced in #9864 by which coroutines are treated as synonymous of function coroutines.

Also, fix the same mistake (coroutines == function coroutines) already present in other parts of the reference.

I'm very sorry for the hassle.

Doc/reference/compound_stmts.rst

@@ -737,16 +737,16 @@ Coroutine function definition
    keyword: await
 
 Execution of Python coroutines can be suspended and resumed at many points
-(see :term:`coroutine`).  In the body of a coroutine, any ``await`` and
+(see :term:`coroutine`).  Inside the body of a coroutine function, ``await`` and
 ``async`` identifiers become reserved keywords; :keyword:`await` expressions,
 :keyword:`async for` and :keyword:`async with` can only be used in
-coroutine bodies.
+coroutine function bodies.
 
 Functions defined with ``async def`` syntax are always coroutine functions,
 even if they do not contain ``await`` or ``async`` keywords.
 
-It is a :exc:`SyntaxError` to use ``yield from`` expressions in
-``async def`` coroutines.
+It is a :exc:`SyntaxError` to use a ``yield from`` expression inside the body
+of a coroutine function.
 
 An example of a coroutine function::
 
@@ -795,8 +795,8 @@ Is semantically equivalent to::
 
 See also :meth:`__aiter__` and :meth:`__anext__` for details.
 
-It is a :exc:`SyntaxError` to use an ``async for`` statement outside of a
-coroutine.
+It is a :exc:`SyntaxError` to use an ``async for`` statement outside the
+body of a coroutine function.
 
 
 .. index:: statement: async with
@@ -833,8 +833,8 @@ Is semantically equivalent to::
 
 See also :meth:`__aenter__` and :meth:`__aexit__` for details.
 
-It is a :exc:`SyntaxError` to use an ``async with`` statement outside of a
-coroutine.
+It is a :exc:`SyntaxError` to use an ``async with`` statement outside the
+body of a coroutine function.
 
 .. seealso::