docs(tutor): move lesson 7.2 below lesson 7.3 #33662

Problem:

- Lesson 7.3 (Cmdline Completion) teaches an important way to discover
  Nvim features. I think users should learn it before they start
  configuring Nvim
- Nvim can be configured in Lua as well, but lesson 7.2 (Configuring
  Nvim) only mentions init.vim. And I think Nvim is promoting Lua more

Solution:

- Move lesson 7.2 to be after lesson 7.3
- Lesson 7.2 should teach about init.lua

Co-authored-by: Justin M. Keyes <justinkz@gmail.com>

test/functional/plugin/tutor_spec.lua

@@ -131,7 +131,7 @@ describe(':Tutor', function()
       {0:  }University. E-mail: {2:bware@mines.colorado.edu}.                                  |
     ]]
 
-    feed(':973<CR>zt')
+    feed(':978<CR>zt')
     screen:expect(expected)
   end)
 end)