feat: Allow passing comment via argument

spec/blueprint/html/utils_spec.cr

@@ -15,6 +15,7 @@ private class DummyPage
     plain "User"
 
     comment { "This is an html comment" }
+    comment "This is another html comment"
   end
 end
 
@@ -36,11 +37,17 @@ describe "Blueprint::HTML utils" do
   end
 
   describe "#comment" do
-    it "renders an html comment" do
+    it "renders an html comment passed via block" do
       page = DummyPage.new
 
       page.to_html.should contain("<!--This is an html comment-->")
     end
+
+    it "renders an html comment passed via argument" do
+      page = DummyPage.new
+
+      page.to_html.should contain("<!--This is another html comment-->")
+    end
   end
 
   describe "#whitespace" do

src/blueprint/html/utils.cr

@@ -13,6 +13,12 @@ module Blueprint::HTML
     @buffer << "-->"
   end
 
+  private def comment(content : String) : Nil
+    @buffer << "<!--"
+    ::HTML.escape(content, @buffer)
+    @buffer << "-->"
+  end
+
   private def whitespace : Nil
     @buffer << " "
   end