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

2018/ferguson/.entry.json

@@ -46,7 +46,7 @@
 	    "inventory_order" : 100,
 	    "OK_to_edit" : true,
 	    "display_as" : "text",
-	    "display_via_github" : false,
+	    "display_via_github" : true,
 	    "entry_text" : "information about various files"
 	},
 	{

2018/ferguson/index.html

@@ -1144,7 +1144,7 @@ email but I’m more likely to respond to mastodon messages.</p>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/Makefile">Makefile</a> - entry Makefile</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/prog.alt.c">prog.alt.c</a> - alternative source</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/prog.orig.c">prog.orig.c</a> - original source</li>
-<li><a href="FILES">FILES</a> - information about various files</li>
+<li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/FILES">FILES</a> - information about various files</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/id.alt.sh">id.alt.sh</a> - how to run</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/id.sh">id.sh</a> - how to run</li>
 <li><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2018/ferguson/monkey-words.alt.sh">monkey-words.alt.sh</a> - how to run</li>