docs: man: workaround ronn Markdown bug

The triple backtick code block was confusing `ronn` causing the token section to flow into the library section.

```
   Token file format
       If  you cannot use passwords, as most Enterprise installations do, you can generate the token via the web interface and then simply save the string in the correct file. Avoid line breaks or you might see: $ gist -l Error: Bad
       credentials

       You can also use Gist as a library from inside your ruby code:
```

Author: lucasrangit

README.md

@@ -156,10 +156,9 @@ setting it to the public URL will not work. Use `unset GITHUB_URL`
 
 If you cannot use passwords, as most Enterprise installations do, you can generate the token via the web interface
 and then simply save the string in the correct file. Avoid line breaks or you might see:
-```
-$ gist -l
-Error: Bad credentials
-```
+
+    $ gist -l
+    Error: Bad credentials
 
 # Library