doc: add -r/--release flag info to tutorial (#2211)

README.md

@@ -41,6 +41,8 @@ There are examples for the different bindings in the `test-crates` folder.
 The name of the package will be the name of the cargo project, i.e. the name field in the `[package]` section of `Cargo.toml`.
 The name of the module, which you are using when importing, will be the `name` value in the `[lib]` section (which defaults to the name of the package). For binaries, it's simply the name of the binary generated by cargo.
 
+When using `maturin build` and `maturin develop` commands, you can compile a performance-optimized program by adding the `-r` or `--release` flag.
+
 ## Python packaging basics
 
 Python packages come in two formats:

guide/src/tutorial.md

@@ -199,6 +199,8 @@ manager).
 
 So let's use maturin to build and install in our current environment.
 
+You can also compile a performance-optimized program by adding the `-r` or `--release` flag for speed testing.
+
 ```shell
 (.venv) ferris@rustbox [~/src/rust/guessing-game] % maturin develop
 🔗 Found pyo3 bindings with abi3 support for Python ≥ 3.8