Iterate on wording

- Keep the "you can" to match other optional bullets
- Elevate the "if #available still works" fact

Co-authored-by: Apollo Zhu <[email protected]>

Author: amartini51

TSPL.docc/ReferenceManual/Attributes.md

@@ -1640,8 +1640,9 @@ The additional result-building methods are as follows:
   or to perform other postprocessing on a result before returning it.
 
 - term `static func buildLimitedAvailability(_ component: Component) -> Component`:
-  Builds a partial result that erases type information for
-  outside a compiler-control statement
+  Builds a partial result that erases type information.
+  You can implement this method to prevent type information
+  from propagating outside a compiler-control statement
   that performs an availability check.
 
 For example, the code below defines a simple result builder
@@ -1741,9 +1742,14 @@ into code that calls the static methods of the result builder type:
   You can define an overload of `buildExpression(_:)`
   that takes an argument of type `()` to handle assignments specifically.
 - A branch statement that checks an availability condition
-  becomes a call to the `buildLimitedAvailability(_:)` method if one is defined.
+  becomes a call to the `buildLimitedAvailability(_:)` method,
+  if that method is implemented.
+  If you don't implement `buildLimitedAvailability(_:)`,
+  then branch statements that check availability
+  use the same transformations as other branch statements.
   This transformation happens before the transformation into a call to
   `buildEither(first:)`, `buildEither(second:)`, or `buildOptional(_:)`.
+
   You use the `buildLimitedAvailability(_:)` method to erase type information
   that changes depending on which branch is taken.
   For example,
@@ -1818,7 +1824,7 @@ into code that calls the static methods of the result builder type:
 
   To solve this problem,
   implement a `buildLimitedAvailability(_:)` method
-  to erase type information.
+  to erase type information by returning a type that's always available.
   For example, the code below builds an `AnyDrawable` value
   from its availability check.
 
@@ -1845,11 +1851,6 @@ into code that calls the static methods of the result builder type:
 
   <!-- Comment block with swifttest for the code listing above is after the end of this bulleted list, due to tooling limitations. -->
 
-  Note that the above code compiled before
-  implementing the `buildLimitedAvailability` method,
-  as its role is not to enable the `if #available` syntax, but to
-  return a type that's always available.
-
 - A branch statement becomes a series of nested calls to the
   `buildEither(first:)` and `buildEither(second:)` methods.
   The statements' conditions and cases are mapped onto