Improve doc navigability for child spec options (#14097)

Author: sabiwara

lib/elixir/lib/gen_server.ex

@@ -203,14 +203,16 @@ defmodule GenServer do
   The generated `child_spec/1` can be customized with the following options:
 
     * `:id` - the child specification identifier, defaults to the current module
-    * `:restart` - when the child should be restarted, defaults to `:permanent`
-    * `:shutdown` - how to shut down the child, either immediately or by giving it time to shut down
+    * [`:restart`](`m:Supervisor#module-restart-values-restart`) - when the
+      child should be restarted, defaults to `:permanent`
+    * [`:shutdown`](`m:Supervisor#module-shutdown-values-shutdown`) - how to
+      shut down the child, either immediately or by giving it time to shut down
 
   For example:
 
       use GenServer, restart: :transient, shutdown: 10_000
 
-  See the "Child specification" section in the `Supervisor` module for more
+  See the ["Child specification"](`m:Supervisor#module-child_spec-1-function`) section in the `Supervisor` module for more
   detailed information. The `@doc` annotation immediately preceding
   `use GenServer` will be attached to the generated `child_spec/1` function.
 

lib/elixir/lib/supervisor.ex

@@ -130,11 +130,11 @@ defmodule Supervisor do
       to start the child process. This key is required.
 
     * `:restart` - an atom that defines when a terminated child process
-       should be restarted (see the "Restart values" section below).
+       should be restarted (see the ["Restart values"](#module-restart-values-restart) section below).
        This key is optional and defaults to `:permanent`.
 
     * `:shutdown` - an integer or atom that defines how a child process should
-      be terminated (see the "Shutdown values" section below). This key
+      be terminated (see the ["Shutdown values"](#module-shutdown-values-shutdown) section below). This key
       is optional and defaults to `5_000` if the type is `:worker` or
       `:infinity` if the type is `:supervisor`.