Add footnote to lwn gcc article

rust-intro.org

@@ -51,7 +51,7 @@
     - Strong type system prevents [[https://doc.rust-lang.org/nomicon/races.html][data races]], brings [[https://blog.rust-lang.org/2015/04/10/Fearless-Concurrency.html]['fearless
       concurrency']] (amongst others).
     - Seamless C interop, and [[https://doc.rust-lang.org/rustc/platform-support.html][dozens of supported platforms]] (based on
-      LLVM).[fn:gcc]
+      LLVM).[fn:lwn_gcc][fn:gcc]
     - [[https://insights.stackoverflow.com/survey/2021#technology-most-loved-dreaded-and-wanted]["Most loved language"]] for 6 years in a row.
     - Modern tooling: ~cargo~ (builds just work), ~clippy~ (450+ code
       quality lints), ~rustup~ (easy toolchain management).
@@ -697,6 +697,7 @@
 [fn:strengths] Copied list from: [[https://cheats.rs/#tab-hello-3][cheats.rs]].
 [fn:weaknesses] Copied list from: [[https://cheats.rs/#tab-hello-4][cheats.rs]].
 [fn:gcc] Work on GCC: [[https://rust-gcc.github.io/][rust-gcc]] and [[https://news.ycombinator.com/item?id=27775544][gcc rust backend]].
+[fn:lwn_gcc] [[https://lwn.net/Articles/871283/][Rust and GCC, two different ways]]
 [fn:survey] [[https://blog.rust-lang.org/2020/04/17/Rust-survey-2019.html#why-not-use-rust][Rust survey]]
 [fn:compiler_speed] [[https://news.ycombinator.com/item?id=23538220][The Rust compiler isn't slow; we are]]
 [fn:specification] [[https://people.mpi-sws.org/%7Ejung/thesis.html][Understanding and Evolving the Rust Programming Language]]