gh-142349: Update lazy import comments in whatsnew (#158651)

* Update lazy import comments in whatsnew

* Correct wording

Author: Sacul0457

Doc/whatsnew/3.15.rst

@@ -188,10 +188,10 @@ name:
    lazy import json
    lazy from pathlib import Path
 
-   print("Starting up...")  # json and pathlib not loaded yet
+   print("Starting up...")  # json and pathlib are not fully imported yet
 
-   data = json.loads('{"key": "value"}')  # json loads here
-   p = Path(".")  # pathlib loads here
+   data = json.loads('{"key": "value"}')  # json gets fully imported here
+   p = Path(".")  # pathlib gets fully imported here
 
 This mechanism is particularly useful for applications that import many
 modules at the top level but may only use a subset of them in any given run.