Merge pull request #14734 from ckipp01/docCommentMarkdown

fix: don't add extra newlines when there aren't extra sections in doc markdown

Author: tgodzik

compiler/src/dotty/tools/dotc/util/ParsedComment.scala

@@ -53,24 +53,26 @@ class ParsedComment(val comment: Comment) {
    *
    * The different sections are formatted according to the mapping in `knownTags`.
    */
-  def renderAsMarkdown(using Context): String = {
+  def renderAsMarkdown(using Context): String =
     val buf = new StringBuilder
-    buf.append(mainDoc + System.lineSeparator + System.lineSeparator)
+    buf.append(mainDoc)
     val groupedSections = CommentParsing.groupedSections(content, tagIndex)
 
-    for {
+    val sections = for {
       (tag, formatter) <- ParsedComment.knownTags
       boundss <- groupedSections.get(tag)
       texts = boundss.map { case (start, end) => clean(content.slice(start, end)) }
       formatted <- formatter(texts)
-    }
-    {
-      buf.append(formatted)
-      buf.append(System.lineSeparator)
-    }
-
+    } yield formatted
+
+    if sections.nonEmpty then
+      buf.append(System.lineSeparator + System.lineSeparator)
+      sections.foreach { section =>
+        buf.append(section)
+        buf.append(System.lineSeparator)
+      }
     buf.toString
-  }
+  end renderAsMarkdown
 
   /**
    * The `@param` section corresponding to `name`.