Merge pull request rails#42749 from pocke/_CI_skip__Add___see_below___notations_to_threading_documentation

[CI skip] Add `(see below)` notations to threading documentation

Author: jonathanhefner

guides/source/threading_and_code_execution.md

@@ -72,7 +72,7 @@ end
 ```
 
 TIP: If you repeatedly invoke application code from a long-running process, you
-may want to wrap using the Reloader instead.
+may want to wrap using the [Reloader](#reloader) instead.
 
 Each thread should be wrapped before it runs application code, so if your
 application manually delegates work to other threads, such as via `Thread.new`
@@ -108,9 +108,10 @@ end
 
 ### Concurrency
 
-The Executor will put the current thread into `running` mode in the Load
-Interlock. This operation will block temporarily if another thread is currently
-either autoloading a constant or unloading/reloading the application.
+The Executor will put the current thread into `running` mode in the [Load
+Interlock](#load-interlock). This operation will block temporarily if another
+thread is currently either autoloading a constant or unloading/reloading
+the application.
 
 Reloader
 --------
@@ -320,4 +321,3 @@ backtrace.
 Generally a deadlock will be caused by the interlock conflicting with some other
 external lock or blocking I/O call. Once you find it, you can wrap it with
 `permit_concurrent_loads`.
-