Add change tracker entry

src/bootstrap/src/core/config/config.rs

@@ -305,7 +305,7 @@ pub struct Config {
     pub save_toolstates: Option<PathBuf>,
     pub print_step_timings: bool,
     pub print_step_rusage: bool,
-    pub missing_tools: bool,
+    pub missing_tools: bool, // FIXME: Deprecated field. Remove it at 2024.
 
     // Fallback musl-root for all targets
     pub musl_root: Option<PathBuf>,

src/bootstrap/src/utils/change_tracker.rs

@@ -101,4 +101,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Warning,
         summary: "rust-analyzer-proc-macro-srv is no longer enabled by default. To build it, you must either enable it in the configuration or explicitly invoke it with x.py.",
     },
+    ChangeInfo {
+        change_id: 119373,
+        severity: ChangeSeverity::Info,
+        summary: "The dist.missing-tools config option was deprecated, as it was unused. If you are using it, remove it from your config, it will be removed soon.",
+    },
 ];