fix: heading render

plugin/gomark/render/html/html.go

@@ -96,7 +96,7 @@ func (r *HTMLRender) renderCodeBlock(node *ast.CodeBlock) {
 }
 
 func (r *HTMLRender) renderHeading(node *ast.Heading) {
-	element := fmt.Sprintf("<h%d>", node.Level)
+	element := fmt.Sprintf("h%d", node.Level)
 	r.output.WriteString(fmt.Sprintf("<%s>", element))
 	r.RenderNodes(node.Children)
 	r.output.WriteString(fmt.Sprintf("</%s>", element))

plugin/gomark/render/html/html_test.go

@@ -18,6 +18,10 @@ func TestHTMLRender(t *testing.T) {
 			text:     "Hello world!",
 			expected: `<p>Hello world!</p>`,
 		},
+		{
+			text:     "# Hello world!",
+			expected: `<h1>Hello world!</h1>`,
+		},
 		{
 			text:     "> Hello\n> world!",
 			expected: `<blockquote>Hello<br>world!</blockquote>`,