Explicitly open markdown links in the same window

We were already opening them in the same window because we were
accidentall sanitizing the `target` attribute, but now we're making the
point more explicit.

lib/markdown_converter.rb

@@ -30,7 +30,7 @@ class MarkdownConverter
       {
         filter_html: false,
         hard_wrap: true,
-        link_attributes: { target: "_blank" }
+        link_attributes: {}
       }
     end
 

spec/models/legislation/draft_version_spec.rb

@@ -38,6 +38,12 @@ describe Legislation::DraftVersion do
     expect(legislation_draft_version.toc_html).to eq(toc_html)
   end
 
+  it "does not add a target attribute to links" do
+    legislation_draft_version.body = "A [link](/url)"
+
+    expect(legislation_draft_version.body_html).to eq("<p>A <a href=\"/url\">link</a></p>\n")
+  end
+
   def body_markdown
     <<~BODY_MARKDOWN
       # Title 1