Update quickhelp

Add info to help user know how to quickly access each layer and
.spacemacas file.

Also fix line end formatting: use unix by default.

core/info/quickhelp.txt

@@ -1,13 +1,25 @@
-Press TAB to move to next button.
-
-Press SHIFT-TAB to move to previous button.
-
-Press r to jump to recent file list.
-
-Press p to jump to project list.
-
-Press m to jump to the top menu.
-
-Press SPC (in Vim mode) or Alt-m (in Emacs mode) to access Spacemacs commands.
-
-Please consult Spacemacs documentation for more details.
+Press TAB to move to next button.
+
+Press SHIFT-TAB to move to previous button.
+
+Press r to jump to recent file list.
+
+Press p to jump to project list.
+
+Press m to jump to the top menu.
+
+Press o to jump to any link or button.
+
+Press SPC (in Vim mode) or Alt-m (in Emacs mode) to access Spacemacs commands.
+
+Press SPC f e d (Vim) or Alm-m f e d (Emacs) to access .spacemacs file.
+
+Press SPC f e h (Vim) or Alt-m f e h (Emacs) to access a list of supported layers.
+You can type anything to narrow to a specific feature i.e. "python" for Python layer.
+There are two lists and you can press C-o to switch between the two:
+
+- the first list gives documentation of each layer.
+
+- the second list gives access to the source code of each layer.
+
+Please consult Spacemacs documentation for more details.