Update exec.py -- fix typo

Author: onkarganjewar

examples/exec.py

@@ -23,7 +23,7 @@
         exit(1)
 
 if not resp:
-    print("Pod %s does not exits. Creating it..." % name)
+    print("Pod %s does not exist. Creating it..." % name)
     pod_manifest = {
         'apiVersion': 'v1',
         'kind': 'Pod',