Add an example doc comment with code block

See #522

Author: cristianoc

analysis/tests/src/Hover.res

@@ -139,11 +139,20 @@ let arity0d = (. ()) => {
   f
 }
 
-/**doc comment 1*/
+/**doc comment `1` one */
 let docComment1 = 12
 //       ^hov
 
-/** doc comment 2 */
+/**
+  Doc comment with a triple-backquote example
+  
+  ```res example
+    let a = 10
+    /*
+     * stuff
+     */
+  ```
+*/
 let docComment2 = 12
 //    ^hov
 

analysis/tests/src/expected/Hover.res.txt

@@ -99,8 +99,8 @@ Hover src/Hover.res 135:5
 {"contents": "```rescript\n(. ()) => unit => int\n```"}
 
 Hover src/Hover.res 142:9
-{"contents": "```rescript\nint\n```\n\ndoc comment 1"}
+{"contents": "```rescript\nint\n```\n\ndoc comment `1` one "}
 
-Hover src/Hover.res 146:6
-{"contents": "```rescript\nint\n```\n\n doc comment 2 "}
+Hover src/Hover.res 155:6
+{"contents": "```rescript\nint\n```\n\nDoc comment with a triple-backquote example\n\ns example\n a = 10\n\nstuff\n\n"}