simplify build (#11)

Remove build.rs for just a standard relative path include.

build scripts are an advanced feature. It just happened that this
particular crate did not play nice with a non-cargo build system.

Likely it would be possible to fix it locally, but I actually don't
see any reason for this crate to have a build.rs

I checked it locally and it seems to produce exactly the same results.

LMK if I am missing something.

proc-macro-warning/Cargo.toml

@@ -8,8 +8,6 @@ description = "Emit warnings from inside proc macros."
 repository = "https://github.com/ggwpez/proc-macro-warning"
 readme.workspace = true
 
-build = "build.rs"
-
 [dependencies]
 proc-macro2 = { version = "1.0.68", default-features = false }
 quote = { version = "1.0.33", default-features = false }

proc-macro-warning/src/lib.rs

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: (GPL-3.0 or Apache-2.0)
  */
 
-#![doc = include_str!(env!("README_PATH"))]
+#![doc = include_str!("../../README.md")]
 #![deny(unsafe_code)]
 #![deny(missing_docs)]