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.
 
 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
 ## Committing
 
 When you submit patches, the project maintainer has to read them and