Tweak documentation

Author: owen-mc

java/ql/src/Performance/StringReplaceAllWithNonRegex.md

@@ -4,7 +4,7 @@ Using `String#replaceAll` is less performant than `String#replace` when the firs
 
 ## Overview
 
-The underlying implementation of `String#replaceAll` uses `Pattern#compile` and expects a regular expression as its first argument. However in cases where the argument could be represented by just a plain `String` that does not represent an interesting regular expression, a call to `String#replace` may be more performant as it does not need to compile the regular expression.
+The `String#replaceAll` method is designed to work with regular expressions as its first parameter. When you use a simple string without any regex patterns (like special characters or syntax), it's more efficient to use `String#replace` instead. This is because `replaceAll` has to compile the input as a regular expression first, which adds unnecessary overhead when you are just replacing literal text.
 
 ## Recommendation
 

java/ql/src/Performance/StringReplaceAllWithNonRegex.ql

@@ -1,8 +1,8 @@
 /**
  * @id java/string-replace-all-with-non-regex
  * @name Use of `String#replaceAll` with a first argument which is not a regular expression
- * @description Using `String#replaceAll` is less performant than `String#replace` when the first
- *              argument is not a regular expression.
+ * @description Using `String#replaceAll` with a first argument which is not a regular expression
+ *              is less efficient than using `String#replace`.
  * @kind problem
  * @precision very-high
  * @problem.severity recommendation