.editorconfig: move subfolder config into separate .editorconfig files

This avoids paths in the top-level file getting out-of-sync, because the
.editorconfig files would be moved together with the files they target.

.editorconfig

···
 [eggs.nix]
 trim_trailing_whitespace = unset
 
-[nixos/modules/services/networking/ircd-hybrid/*.{conf,in}]
-trim_trailing_whitespace = unset
-
-[pkgs/build-support/dotnet/dotnetenv/Wrapper/**]
-end_of_line = unset
-indent_style = unset
-insert_final_newline = unset
-trim_trailing_whitespace = unset
-
 [registry.dat]
 end_of_line = unset
 insert_final_newline = unset
 
-[pkgs/development/haskell-modules/hackage-packages.nix]
-indent_style = unset
-trim_trailing_whitespace = unset
-
-[pkgs/misc/documentation-highlighter/**]
-insert_final_newline = unset
-
-[pkgs/servers/dict/wordnet_structures.py]
-trim_trailing_whitespace = unset
-
-[pkgs/by-name/ti/timidity/timidity.cfg]
-trim_trailing_whitespace = unset
-
-[pkgs/tools/security/qdigidoc/vendor/*]
-end_of_line = unset
-insert_final_newline = unset
-trim_trailing_whitespace = unset
-
-[pkgs/by-name/ov/ovftool/*.ova]
-end_of_line = unset
-insert_final_newline = unset
-trim_trailing_whitespace = unset
-charset = unset
-
-[lib/tests/*.plist]
-indent_style = tab
-insert_final_newline = unset
-
-[pkgs/kde/generated/**]
-insert_final_newline = unset
-end_of_line = unset
+# Keep this hint at the bottom:
+# Please don't add entries for subfolders here.
+# Create <subfolder>/.editorconfig instead.

lib/tests/.editorconfig

···
+[*.plist]
+indent_style = tab
+insert_final_newline = unset

nixos/modules/services/networking/ircd-hybrid/.editorconfig

···
+[*.{conf,in}]
+trim_trailing_whitespace = unset

pkgs/build-support/dotnet/dotnetenv/Wrapper/.editorconfig

···
+[*]
+end_of_line = unset
+indent_style = unset
+insert_final_newline = unset
+trim_trailing_whitespace = unset

pkgs/by-name/ov/ovftool/.editorconfig

···
+[*.ova]
+end_of_line = unset
+insert_final_newline = unset
+trim_trailing_whitespace = unset
+charset = unset

pkgs/by-name/ti/timidity/.editorconfig

···
+[timidity.cfg]
+trim_trailing_whitespace = unset

pkgs/development/haskell-modules/.editorconfig

···
+[hackage-packages.nix]
+indent_style = unset
+trim_trailing_whitespace = unset

pkgs/kde/generated/.editorconfig

···
+[*]
+insert_final_newline = unset
+end_of_line = unset

pkgs/misc/documentation-highlighter/.editorconfig

···
+[*]
+insert_final_newline = unset

pkgs/servers/dict/.editorconfig

···
+[wordnet_structures.py]
+trim_trailing_whitespace = unset

pkgs/tools/security/qdigidoc/vendor/.editorconfig

···
+[*]
+end_of_line = unset
+insert_final_newline = unset
+trim_trailing_whitespace = unset