README: Include a note about --no-self-update
@@ -176,6 +176,10 @@ info: checking for self-updates
info: downloading self-updates
```
+**Note**: `rustup` will automatically update itself at the end of any toolchain
+installation as well. You can prevent this automatic behaviour by passing the
+`--no-self-update` argument when running `rustup update` or `rustup toolchain install`.
+
## Working with nightly Rust
Rustup gives you easy access to the nightly compiler and its
