Added a tutorial "Improve internal linking of link-module with Linkit"

Here the tutorial: https://www.drupal.org/node/2573127

Please have a look & review and maybe add it also on the module page:
The behaviour of linking to internal entities (e.g. nodes) could be much improved with the integration of the "Linkit"-module.

• Step 1: Install and enable the Linkit-Module
• Step 2: Create a field profile (admin/config/content/linkit): ADD NEW PROFILE with "Profile Type" of "Fields"
  
• Step 3: Profile configuration:
  
  - Select your needed entity types on Tab "Search plugins" and improve the display (Result description) for the user via "NODE PLUGIN SETTING": Title:[node:title] / URL alias:[node:url]
  
  - Set "Insert method", "Raw URL" & "Raw paths ..." is recommended
  - Set other wanted options
  
  
  
  
  
• Step 4: got to your content type and configure the field settings: click checkbox "Enable Linkit for this field." and choose "Profile". Don´t type "Internal links" wrong ;-)
  
  
• Step 5: have a happy internal linking