Sublime docs: Use unix line endings by default

docs/linux_sublime_dev.md

 # Linux Sublime Dev
 
 Sublime Text is a fast, powerful and easily extensible code editor. Check out
 some [visual demos](http://www.sublimetext.com) for a quick demonstration.
 
 You can download and install Sublime Text 3 from the [Sublime Text
 Website](http://www.sublimetext.com/3). Assuming you have access to the right
 repositories, you can also install Sublime via apt-get on Linux. Help and
 general documentation is available in the [Sublime Text 3
 Docs](http://www.sublimetext.com/docs/3/).
@@ skipping 55 matching lines @@
   "trim_trailing_white_space_on_save": true,
   "ensure_newline_at_eof_on_save": true,
   "translate_tabs_to_spaces" : true,
 
   // Optional, but also useful, preferences
   "always_show_minimap_viewport": true,
   "bold_folder_labels": true,
   "draw_white_space": "all",
   "enable_tab_scrolling": false,
   "highlight_line": true,
+
+  // Mainly for Windows, but harmless on Mac/Linux
+  "default_line_ending": "unix",
 }
 ```
 
 The settings will take effect as soon as you save the file.
 
 #### Tips
 *   `View > Side Bar > Show Open Files` will add a list of open files to the top
     of the sidebar
 *   ``Ctrl+` `` will show the console; it shows errors and debugging output, and
     you can run Python
@@ skipping 488 matching lines @@
     *   [Case Conversion](https://packagecontrol.io/packages/Case%20Conversion) -
         automatically changes the case of selected text, e.g. `kConstantName` to
         `CONSTANT_NAME`
     *   [Text Pastry](https://packagecontrol.io/packages/Text%20Pastry) -
         Inserts incremental number sequences with multi-select
     *   [Wrap Plus](https://packagecontrol.io/packages/Wrap%20Plus) - Auto-wraps
         a comment block to 80 columns with `Alt + Q` (was used to write this
         document! ;-)
     *   [Diffy](https://packagecontrol.io/packages/Diffy) - With two files
         opened side-by-side, `Ctrl + k Ctrl + d` will show the differences