Update .editorconfig (#10518)

* Update .editorconfig

* Remove webapp-specific entries from .editorconfig

.editorconfig

@@ -6,6 +6,7 @@ root = true
 end_of_line = lf
 insert_final_newline = true
 charset = utf-8
+trim_trailing_whitespace = true
 
 [*.go]
 indent_style = tab
@@ -14,18 +15,13 @@ indent_style = tab
 indent_style = space
 indent_size = 4
 
-[webapp/package.json]
-indent_size = 2
-
 [i18n/**.json]
 indent_size = 2
 
-[webapp/i18n/**.json]
-indent_size = 2
-
-[Makefile]
+[Makefile,*.mk]
 indent_style = tab
 
-[*.scss]
+[*.md]
 indent_style = space
 indent_size = 4
+trim_trailing_whitespace = false