Make it clear what verified users can vote for

"Participate in the final voting" was a concept which was hard to
understand since many people would think it was related to the
voting/polls section and that somehow there was going to be a "final"
poll.

So we use "Vote for budget projects" instead.

Thanks Pomerange for the suggestion.

spec/system/management/document_verifications_spec.rb

@@ -20,7 +20,7 @@ describe "DocumentVerifications" do
     fill_in "document_verification_document_number", with: user.document_number
     click_button "Check document"
 
-    expect(page).to have_content "Participate in final voting"
+    expect(page).to have_content "Vote for budget projects"
 
     click_button "Verify"