Rephrase description of rust-client.updateOnStartup setting

Fixes #407

Author: Xanewok

package.json

@@ -194,7 +194,7 @@
                 "rust-client.updateOnStartup": {
                     "type": "boolean",
                     "default": false,
-                    "description": "Update the RLS whenever the extension starts up."
+                    "description": "Update the Rust toolchain and its required components whenever the extension starts up."
                 },
                 "rust-client.autoStartRls": {
                     "type": "boolean",