set variable for file to check

build/main.sh

 #!/bin/bash
+CHECK_FILE=../README.md
 echo "running format validation..."
-./validate_format.rb ../README.md
+./validate_format.rb $CHECK_FILE
 if [[ $? != 0 ]]; then
     echo "format validation failed!"
     exit 1
@@ -10,7 +11,7 @@ fi
 
 if [ "$TRAVIS_BRANCH" == "master" ]; then
     echo "running link validation..."
-    ./validate_links.rb ../README.md
+    ./validate_links.rb $CHECK_FILE
     if [[ $? != 0 ]]; then
         echo "link validation failed!"
         exit 1