Add examples for env,let-env,rm,touch and date list-timezone (#4531)

* feat: update #4518, add examples for env,let-env,rm,touch and date list-timezone

* fix typo

* update example for `date list-timezone` command

crates/nu-command/src/env/let_env.rs

@@ -1,7 +1,7 @@
 use nu_engine::{current_dir, eval_expression_with_input, CallExt};
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
-use nu_protocol::{Category, PipelineData, Signature, SyntaxShape, Value};
+use nu_protocol::{Category, Example, PipelineData, Signature, SyntaxShape, Value};
 
 #[derive(Clone)]
 pub struct LetEnv;
@@ -58,4 +58,12 @@ impl Command for LetEnv {
         }
         Ok(PipelineData::new(call.head))
     }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Create an environment variable and display it",
+            example: "let-env MY_ENV_VAR = 1; $env.MY_ENV_VAR",
+            result: Some(Value::test_int(1)),
+        }]
+    }
 }