doc: simplify "is recommended" language in assert documentation

Replace "X is not recommended" with "Avoid X".
Replace "It is recommended not to use X" with "Avoid X".
PR-URL: #30558
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

Author: Trott

doc/api/assert.md

@@ -1234,10 +1234,11 @@ assert.throws(
  (err) => {
 assert(err instanceofError);
 assert(/value/.test(err));
-// Returning anything from validation functions besides `true` is not
-// recommended. Doing so results in the caught error being thrown again.
-// That is usually not the desired outcome. Throw an error about the
-// specific validation that failed instead (as done in this example).
+// Avoid returning anything from validation functions besides `true`.
+// Otherwise, it's not clear what part of the validation failed. Instead,
+// throw an error about the specific validation that failed (as done in this
+// example) and add as much helpful debugging information to that error as
+// possible.
 returntrue;
  },
 'unexpected error'
@@ -1288,8 +1289,8 @@ assert.throws(throwingFirst, /Second$/);
 // at throwingFirst (repl:2:9)
 ```
 
-Due to the confusing notation, it is recommended not to use a string as the
-second argument. This might lead to difficult-to-spot errors.
+Due to the confusing error-prone notation, avoid a string as the second
+argument.
 
 [`Class`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes
 [`ERR_INVALID_RETURN_VALUE`]: errors.html#errors_err_invalid_return_value