Update README.md

PR: #53
Signed-off-by: Char ma <test@mail.com>
Reviewed-by: Charalampos Mainas <cmainas@nubificus.co.uk>
Approved-by: Charalampos Mainas <cmainas@nubificus.co.uk>

Author: charma7

README.md

@@ -1,5 +1,7 @@
 # urunc
 
+This is only for testing.
+
 [![OpenSSF Best Practices](https://www.bestpractices.dev/projects/10840/badge)](https://www.bestpractices.dev/projects/10840)
 
 Welcome to `urunc`, the "runc for unikernels".