Update cifuzz.yml

There's no need to run fuzzer on .md changes

Author: zeux

.github/workflows/cifuzz.yml

@@ -1,5 +1,10 @@
 name: CIFuzz
-on: [pull_request]
+
+on:
+  pull_request:
+    paths-ignore:
+      - '*.md'
+
 jobs:
   Fuzzing:
     runs-on: ubuntu-latest