ignore/types: add Kconfig

Kconfig files are used to represent the configuration database of Kbuild
build system.
Kbuild is developed as part of the Linux kernel.
There are numerous other users including OpenWrt and U-Boot.

Ref: https://docs.kernel.org/kbuild/index.html

crates/ignore/src/default_types.rs

@@ -117,6 +117,7 @@ pub(crate) const DEFAULT_TYPES: &[(&[&str], &[&str])] = &[
     (&["julia"], &["*.jl"]),
     (&["jupyter"], &["*.ipynb", "*.jpynb"]),
     (&["k"], &["*.k"]),
+    (&["kconfig"], &["Kconfig", "Kconfig.*"]),
     (&["kotlin"], &["*.kt", "*.kts"]),
     (&["lean"], &["*.lean"]),
     (&["less"], &["*.less"]),