change test files that do not end in .txt to view via GitHub

2019/burton/.entry.json

@@ -134,7 +134,7 @@
 	    "inventory_order" : 4294967295,
 	    "OK_to_edit" : true,
 	    "display_as" : "text",
-	    "display_via_github" : false,
+	    "display_via_github" : true,
 	    "entry_text" : "more useful interface."
 	}
     ]

2019/burton/index.html

@@ -234,7 +234,7 @@ This exercise left to the reader.</p>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2019/burton/README.md">README.md</a> - markdown source for this web page</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2019/burton/.entry.json">.entry.json</a> - description of entry in JSON</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2019/burton/.gitignore">.gitignore</a> - list of files that should not be committed under git</li>
-<li><a href="newlines">newlines</a> - more useful interface.</li>
+<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2019/burton/newlines">newlines</a> - more useful interface.</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2019/burton/.path">.path</a> - directory path from top directory</li>
 </ul>