Outputs parameter comments using clang-doc and markdown generator

[BotellaA]

Summary

Current implementation outputs the parameter name when used with @param (or @tparam) doxygen tag but not the comment itself.

[BotellaA]

I updated the expected result in the MD generator test.
There was already a comment for some parameters but they were not outputted and not included in the test

[aaron.ballman]

I'm not a typical reviewer for clang-doc, so take this with a grain of salt, but LGTM! Do you need someone to land the changes on your behalf? If so, what name and email address would you like used for patch attribution? (I'll leave the review up for a few days in case other reviewers have comments.)

[BotellaA]

Thanks.
You can use this name Arnaud Botella with this email [e-mail].

clang-tools-extra/clang-doc/MDGenerator.cpp

static void writeDescription(const CommentInfo &I, raw_ostream &OS) {
   } else if (I.Kind == "BlockCommandComment") {
     OS << genEmphasis(I.Name);
     for (const auto &Child : I.Children)
       writeDescription(*Child, OS);
   } else if (I.Kind == "InlineCommandComment") {
     OS << genEmphasis(I.Name) << " " << I.Text;
   } else if (I.Kind == "ParamCommandComment") {
     std::string Direction = I.Explicit ? (" " + I.Direction).str() : "";
-    OS << genEmphasis(I.ParamName) << I.Text << Direction << "\n\n";
+    OS << genEmphasis(I.ParamName) << I.Text << Direction;
+    for (const auto &Child : I.Children)
+      writeDescription(*Child, OS);
   } else if (I.Kind == "TParamCommandComment") {
     std::string Direction = I.Explicit ? (" " + I.Direction).str() : "";
-    OS << genEmphasis(I.ParamName) << I.Text << Direction << "\n\n";
+    OS << genEmphasis(I.ParamName) << I.Text << Direction;
+    for (const auto &Child : I.Children)
+      writeDescription(*Child, OS);
   } else if (I.Kind == "VerbatimBlockComment") {
     for (const auto &Child : I.Children)
       writeDescription(*Child, OS);
   } else if (I.Kind == "VerbatimBlockLineComment") {
     OS << I.Text;
     writeNewLine(OS);
   } else if (I.Kind == "VerbatimLineComment") {
     OS << I.Text;

clang-tools-extra/unittests/clang-doc/MDGeneratorTest.cpp

 <li>
 
  Testing.</ul>
 
 
 
  The description continues.
 
-**I** [out]
+**I** [out] is a parameter.
 
-**J**
+**J** is a parameter.
 
 **return**void
 
 )raw";
 
   EXPECT_EQ(Expected, Actual.str());
 }
 
 } // namespace doc
 } // namespace clang