add Markdown to [extras]

Author: ablaom

Project.toml

@@ -18,9 +18,10 @@ CategoricalArrays = "324d7699-5711-5eae-9e2f-1d82baa6b597"
 DataFrames = "a93c6f00-e57d-5684-b7b6-d8193f3e46c0"
 Distances = "b4f34e82-e78d-54a5-968a-f98e89d6e8f7"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
+Markdown = "d6f4376e-aef5-505a-96c1-9c027394607a"
 ScientificTypes = "321657f4-b219-11e9-178b-2701a2544e81"
 Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["CategoricalArrays", "DataFrames", "Distances", "InteractiveUtils", "ScientificTypes", "Tables", "Test"]
+test = ["CategoricalArrays", "DataFrames", "Distances", "InteractiveUtils", "Markdown", "ScientificTypes", "Tables", "Test"]