Update test scenario to test file hashes

It is a simple test scenario which tries to modify a doc file to hit a
RPM integrity issue. Specially in containers the number of packages
tends to be very small and not always there is a TODO file. So it was
also included a README file in the search, which is more common. The
test scenario could also ensure a package is installed but this would
make the test scenario longer than necessary.

linux_os/guide/system/software/integrity/software-integrity/rpm_verification/rpm_verify_hashes/tests/bad_document.fail.sh

@@ -1,8 +1,7 @@
 #!/bin/bash
-#
 
 # find all TODO files in /usr/share/doc and get first of them
-todo_file=$(find /usr/share/doc -name TODO | head -n 1)
+todo_file=$(find /usr/share/doc -name TODO -o -name README | head -n 1)
 
 # append space to that file, so it will change digest
 echo " " >> $todo_file