fix(bashkit): include clap-builtins guide inside crate for cargo publish

Same fix as commit a9f8b51 (v0.4.1) but applied on top of the v0.4.0
tag commit so that re-running the v0.4.0 publish workflow can succeed.
Allows bashkit 0.4.0 to land on crates.io alongside the 0.4.0 PyPI/npm
packages.

Author: chaliy

docs/clap-builtins.md crates/bashkit/docs/clap-builtins.mddocs/clap-builtins.md renamed to crates/bashkit/docs/clap-builtins.md

@@ -2795,7 +2795,7 @@ pub mod custom_builtins_guide {}
 ///
 /// **Related:** [`ClapBuiltin`], [`BashkitContext`], [`BashBuilder::builtin`], [`custom_builtins_guide`]
 #[cfg(feature = "clap-builtins")]
-#[doc = include_str!("../../../docs/clap-builtins.md")]
+#[doc = include_str!("../docs/clap-builtins.md")]
 pub mod clap_builtins_guide {}
 
 /// Bash compatibility scorecard.