skip CI tests for all markdown files

Author: sjpb

.github/workflows/stackhpc.yml

@@ -9,8 +9,7 @@ on:
       - '**'
       - '!dev/**'
       - 'dev/setup-env.sh'
-      - '!docs/**'
-      - '!README.md'
+      - '!**.md'
       - '!.gitignore'
       - '!.github/workflows/'
       - '.github/workflows/stackhpc'
@@ -19,8 +18,7 @@ on:
       - '**'
       - '!dev/**'
       - 'dev/setup-env.sh'
-      - '!docs/**'
-      - '!README.md'
+      - '!**.md'
       - '!.gitignore'
       - '!.github/workflows/'
       - '.github/workflows/stackhpc'