Clarify comment about forcing lld linker

Updated comment to clarify reason for using lld linker. Copied from #664 

@aokblast the comments should explain "why", not just what the line below is doing

intercept-preload/build.rs

@@ -66,7 +66,7 @@ fn main() {
             println!("cargo:rustc-cdylib-link-arg=-Wl,--version-script={}", exports_path);
             // Set rpath to look for dependencies in the same directory as the library
             println!("cargo:rustc-link-arg=-Wl,-rpath,$ORIGIN");
-            // Force using lld
+            // Force using lld, because GNU ld does not support multiple version tag
             // https://users.rust-lang.org/t/how-to-use-linker-version-scripts-in-rust-1-54
             println!("cargo:rustc-cdylib-link-arg=-fuse-ld=lld");
         }