cli: delete builtin update/up aliases

These don't seem used much, and maybe we (or a customized build) will
want to use the name in the future.

CHANGELOG.md

@@ -47,6 +47,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `merge-tools.<name>.edit-args` now requires `$left`/`$right` parameters.
   The default is `edit-args = ["$left", "$right"]`.
 
+* The builtin `jj update` and `jj up` aliases for `jj checkout` have been
+  deleted.
+
 ### New features
 
 * The default log format now uses the committer timestamp instead of the author

src/commands/mod.rs

@@ -195,7 +195,7 @@ struct ConfigEditArgs {
 /// For more information, see
 /// https://github.com/martinvonz/jj/blob/main/docs/working-copy.md.
 #[derive(clap::Args, Clone, Debug)]
-#[command(visible_aliases = &["co", "update", "up"])]
+#[command(visible_aliases = &["co"])]
 struct CheckoutArgs {
     /// The revision to update to
     revision: RevisionArg,