Update f-string description

src/core_codemods/docs/pixee_python_remove-unnecessary-f-str.md

@@ -1,4 +1,9 @@
-This codemod converts any f-strings without interpolation to regular strings.
+This codemod converts any f-strings without interpolated variables into regular strings.
+In these cases the use of f-string is not necessary; a simple string literal is sufficient. 
+
+While in some (extreme) cases we might expect a very modest performance
+improvement, in general this is a fix that improves the overall cleanliness and
+quality of your code.
 
 ```diff
 - var = f"hello"

src/core_codemods/remove_unnecessary_f_str.py

@@ -14,10 +14,14 @@ class RemoveUnnecessaryFStr(BaseCodemod, UnnecessaryFormatString):
     SUMMARY = "Remove Unnecessary F-strings"
     DESCRIPTION = UnnecessaryFormatString.DESCRIPTION
     REFERENCES = [
+        {
+            "url": "https://pylint.readthedocs.io/en/latest/user_guide/messages/warning/f-string-without-interpolation.html",
+            "description": "",
+        },
         {
             "url": "https://github.com/Instagram/LibCST/blob/main/libcst/codemod/commands/unnecessary_format_string.py",
             "description": "",
-        }
+        },
     ]
 
     def __init__(self, codemod_context: CodemodContext, *codemod_args):