fix word_cloud.rst typo

doc/public/course_data_formats/word_cloud/word_cloud.rst

@@ -18,7 +18,7 @@ The following attributes can be specified for this tag::
     [display_name| AUTOGENERATE] – Display name of xmodule. When this attribute is not defined - display name autogenerate with some hash.
     [num_inputs| 5] – Number of inputs.
     [num_top_words| 250] – Number of max words, which will be displayed.
-    [display_student_percents| True] – Dispaly usage percents for each word.
+    [display_student_percents| True] – Display usage percents for each word.
 
 .. note::