[LLDB][NFC] Add clarifying comments for AddCXXSummary and AddCXXSynthetic

Adding comments to AddCXXSynthetic and AddCXXSummary to better explain what they are doing.

GitOrigin-RevId: d9c9c0b2db0dc4ddf407edcafba0a5a806850ddc
diff --git a/include/lldb/DataFormatters/FormattersHelpers.h b/include/lldb/DataFormatters/FormattersHelpers.h
index a5b0da5..8928070 100644
--- a/include/lldb/DataFormatters/FormattersHelpers.h
+++ b/include/lldb/DataFormatters/FormattersHelpers.h
@@ -36,11 +36,13 @@
                        ConstString type_name, TypeSummaryImpl::Flags flags,
                        bool regex = false);
 
+/// Add a summary that is implemented by a C++ callback.
 void AddCXXSummary(TypeCategoryImpl::SharedPointer category_sp,
                    CXXFunctionSummaryFormat::Callback funct,
                    const char *description, ConstString type_name,
                    TypeSummaryImpl::Flags flags, bool regex = false);
 
+/// Add a synthetic that is implemented by a C++ callback.
 void AddCXXSynthetic(TypeCategoryImpl::SharedPointer category_sp,
                      CXXSyntheticChildren::CreateFrontEndCallback generator,
                      const char *description, ConstString type_name,