fix(docs): align engine guidance

Document the actual CLI and Jest engine defaults and the LibAFL options we support so users do not configure the wrong backend by following stale docs.

Author: oetr

README.md

@@ -48,8 +48,8 @@ To use Jazzer.js in your own project follow these few simple steps:
    npx jazzer FuzzTarget
    ```
 
-   To run with the LibAFL backend instead of the default libFuzzer backend, add
-   `--engine=afl`.
+   CLI fuzzing uses the LibAFL backend by default. To run with libFuzzer
+   instead, add `--engine=libfuzzer`.
 
 4. Enjoy fuzzing!
 

docs/fuzz-settings.md

@@ -591,7 +591,7 @@ Instead use the native Jest flag `--testNamePattern` as described above.
 
 ### `engine` : [string]
 
-Default: "libfuzzer"
+Default: `"libafl"` in CLI mode, `"libfuzzer"` in Jest mode
 
 Select the native fuzzing backend.
 
@@ -612,7 +612,7 @@ npx jazzer my-fuzz-file --engine=afl
 }
 ```
 
-_Note:_ The LibAFL backend currently supports _fuzzing_ mode only.
+LibAFL supports both `fuzzing` and `regression` mode.
 
 ### `fuzzerOptions` : [array\<string\>]
 
@@ -630,6 +630,7 @@ For `engine=afl`/`engine=libafl`, Jazzer.js currently supports these options:
 - `-max_len=<N>`
 - `-max_total_time=<seconds>`
 - `-artifact_prefix=<path-prefix>`
+- `-dict=<path>`
 - non-flag entries interpreted as corpus directories
 
 Unsupported engine-specific flags are rejected with an explicit error.