fix: render LTI variable substitution API docs correctly

why:
* the comment was formatted incorrectly which caused
rake doc:api to leave an extra open code block

refs QUIZ-10351
flag=none

test plan:
* run rake doc:api
* there should be no changes
* go to http://canvas.docker/doc/api/file.tools_variable_substitutions.html
* search for "student view"
* everything below it should be correctly formatted

Change-Id: I0c5ab8065f0064e150f33d1cc4a2a645d7791ed5
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/338605
Reviewed-by: Steve Mcgee <steve.mcgee@instructure.com>
QA-Review: Steve Mcgee <steve.mcgee@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Product-Review: Xander Moffatt <xmoffatt@instructure.com>

doc/api/tools_variable_substitutions.md

@@ -257,6 +257,10 @@ Returns true if the user is launching from student view.
 **Availability**: *when launched by a logged in user*  
 **Launch Parameter**: *com_instructure_user_student_view*  
 
+```
+"true"
+"false"
+```
 ## com.instructure.Observee.sisIds
 returns all observee ids linked to this observer as an String separated by `,`.
 

lib/lti/variable_expander.rb

@@ -319,8 +319,8 @@ module Lti
     #
     # @example
     #   ```
-    #  "true"
-    #  "false"
+    #   "true"
+    #   "false"
     #   ```
     register_expansion "com.instructure.User.student_view",
                        [],