Add examples for receiving data from a job (#16372)

# Description

The existing examples cover how to send data to a job, but I think it
will be much more common to want to receive data from a job.

# User-Facing Changes

Just documentation, though it may be worth highlighting anyway. I really
thought for a while that this was not possible yet. See also my book PR
https://github.com/nushell/nushell.github.io/pull/2006 (`job send` and
`job recv` were not documented in the book at all).

crates/nu-command/src/experimental/job_recv.rs

@@ -116,6 +116,11 @@ in no particular order, regardless of the specified timeout parameter.
                 description: "Get a message or fail if no message is available immediately",
                 result: None,
             },
+            Example {
+                example: "job spawn { sleep 1sec; 'hi' | job send 0 }; job recv",
+                description: "Receive a message from a newly-spawned job",
+                result: None,
+            },
         ]
     }
 }

crates/nu-command/src/experimental/job_send.rs

@@ -101,10 +101,17 @@ This command never blocks.
     }
 
     fn examples(&self) -> Vec<Example> {
-        vec![Example {
+        vec![
+            Example {
                 example: "let id = job spawn { job recv | save sent.txt }; 'hi' | job send $id",
-            description: "Send a message to a newly spawned job",
+                description: "Send a message from the main thread to a newly-spawned job",
                 result: None,
-        }]
+            },
+            Example {
+                example: "job spawn { sleep 1sec; 'hi' | job send 0 }; job recv",
+                description: "Send a message from a newly-spawned job to the main thread (which always has an ID of 0)",
+                result: None,
+            },
+        ]
     }
 }