Fix option tag handling with no data types

Do not error if no data types are provided to the option tag.
Instead, generate a suitable line excluding the data type.

Author: seanmil

lib/puppet-strings/markdown/templates/classes_and_defines.erb

@@ -70,7 +70,11 @@ Data type:<%= code_maybe_block(param[:types].join(', ')) %>
 Options:
 
 <% options_for_param(param[:name]).each do |o| -%>
+<% if o[:opt_types] -%>
 * **<%= o[:opt_name] %>** `<%= o[:opt_types][0] %>`: <%= o[:opt_text] %>
+<% else -%>
+* **<%= o[:opt_name] %>**: <%= o[:opt_text] %>
+<% end -%>
 <% end -%>
 
 <% end -%>