Add test case for new comment syntax

syntaxes/test/_comments.rst

@@ -8,4 +8,24 @@
 -- ^^^^^^^^^^^^^^^^^^^^^^^^ comment.block
 
 However... lines that contain ellipses should NOT be a comment.
---      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -comment.block
+--      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -comment.block
+
+..
+   multiline comment that starts on the next line
+-- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ comment.block
+
+   should continue after blank lines
+-- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ comment.block
+   including paragraphs
+-- ^^^^^^^^^^^^^^^^^^^^ comment.block
+
+..
+
+   when the first line is blank, it's not a comment
+-- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -comment.block
+
+...three dots should not start a comment
+-- <------ -comment.block
+
+..also needs spaces after the two dots
+-- <------ -comment.block