Provide a docs link for the first error every knife user gets

This one confused me the first time I used Chef and judging by the number of questions / views on stack overflow I'm not the only person. Lets just link to the docs here so people can quickly figure out what needs to be set and how.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/chef/knife/edit.rb b/lib/chef/knife/edit.rb
index 5275f3c59b..8489e4e179 100644
--- a/lib/chef/knife/edit.rb
+++ b/lib/chef/knife/edit.rb
@@ -58,7 +58,7 @@ class Chef
 
             # Let the user edit the temporary file
             if !system("#{config[:editor]} #{file.path}")
-              raise "Please set EDITOR environment variable"
+              raise "Please set EDITOR environment variable. See https://docs.chef.io/knife_using.html for details."
             end
 
             result_text = IO.read(file.path)