chore: Add a note to cargo config about RUSTFLAGS in the web build

.cargo/config.toml

@@ -1,4 +1,5 @@
 [target.'cfg(all())']
+# NOTE that the web build overrides this setting in package.json via the RUSTFLAGS environment variable
 rustflags = [
     # CLIPPY LINT SETTINGS
     # This is a workaround to configure lints for the entire workspace, pending the ability to configure this via TOML.
@@ -7,7 +8,7 @@ rustflags = [
 
     # Clippy nightly often adds new/buggy lints that we want to ignore.
     # Don't warn about these new lints on stable.
-    "-Arenamed_and_removed_lints", 
+    "-Arenamed_and_removed_lints",
     "-Aunknown_lints",
 
     # LONG-TERM: These lints are unhelpful.