Remove section on removed rake doc:app

Remove the section of contributing docs about how `rake doc:app` can be used to generate some sort of documentation. That will not work any more, since this task was removed from Rails v5 because people don't generally use it! https://stackoverflow.com/a/36804474/338265

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 61e23f810d39b921ef717ba7e723ced5f9366221..aaa1b5d4b555b960d3d5a258e660c78f0ff6afe3 100644 (file)
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -79,14 +79,6 @@ database, and update the list of available keys manually.
 Adding or removing keys to this list is therefore discouraged, but contributions
 to the descriptive texts are welcome.
 
-## Code Documentation
-
-To generate the HTML documentation of the API/rails code, run the command
-
-```
-rake doc:app
-```
-
 ## Committing
 
 When you submit patches, the project maintainer has to read them and