Add abi_x86_interrupt to the unstable book

Author: topecongiro

src/doc/unstable-book/src/SUMMARY.md

@@ -5,6 +5,7 @@
 - [abi_sysv64](abi-sysv64.md)
 - [abi_unadjusted](abi-unadjusted.md)
 - [abi_vectorcall](abi-vectorcall.md)
+- [abi_x86_interrupt](abi-x86-interrupt.md)
 - [advanced_slice_patterns](advanced-slice-patterns.md)
 - [alloc_jemalloc](alloc-jemalloc.md)
 - [alloc_system](alloc-system.md)

src/doc/unstable-book/src/abi-x86-interrupt.md

@@ -0,0 +1,7 @@
+# `abi_x86_interrupt`
+
+The tracking issue for this feature is: [#40180]
+
+[#40180]: https://github.com/rust-lang/rust/issues/40180
+
+------------------------