Update test_harness/single_node/README.md

Co-authored-by: Kory Draughn <korydraughn@ymail.com>

Author: d-w-moore

test_harness/single_node/README.md

@@ -2,7 +2,7 @@
 
 ## Description
 
-A series of docker images which support running isolated test scripts (using BATS, bash, or Python).
+A series of Docker images which support running isolated test scripts (using BATS, bash, or Python).
 Once built, the images allow loading and customizing the Docker container environment for a given 
 test script.