converting tabs to spaces for all markdown, adding editorconfig

Author: getify

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = tab
+indent_size = 4
+
+[*.md]
+indent_style = space
+indent_size = 4