Add command for running a single input

xcm/xcm-simulator/fuzzer/README.md

@@ -8,6 +8,12 @@ This project will fuzz-test the XCM simulator. It can catch reachable panics, ti
 cargo hfuzz run xcm-fuzzer
 ```
 
+## Run a single input
+
+```
+cargo hfuzz run-debug xcm-fuzzer hfuzz_workspace/xcm-fuzzer/fuzzer_input_file
+```
+
 ## Generate coverage
 
 In this directory, run these four commands:
@@ -19,4 +25,4 @@ zip -0 ccov.zip `find ../../../target/ \( -name "*.gc*" -o -name "test-*.gc*" \)
 grcov ccov.zip -s ../../../ -t html --llvm --branch --ignore-not-existing -o ./coverage
 ```
 
-The code coverage will be in `./coverage/index.html`.
+The code coverage will be in `./coverage/index.html`.