[#672] DeveloperGuide: Update instructions on setting up (#691)
[#672] DeveloperGuide: Update instructions on setting up (#691)

HelpWindowTest fails if the processResources task isn’t executed by
Gradle before the test runs.

This isn’t documented in the DeveloperGuide, which may cause confusion
to future developers if they encounter this issue.

Let’s update the setting up instructions in DeveloperGuide to reflect
this issue.
damithc/addressbook-level4,damithc/addressbook-level4,damithc/addressbook-level4,se-edu/addressbook-level3