Doc: Update installation instructions to use pip

docs/source/installation.md

@@ -1,16 +1,45 @@
 (installation)=
 # Installation
 
-We recommend using [Anaconda](https://www.anaconda.com/) (or [Miniforge](https://github.com/conda-forge/miniforge)) to install Python on your local machine, which allows for packages to be installed using its `conda` utility.
+As of PyMC v6, PyMC compiles models with the [Numba](https://numba.pydata.org/) backend by
+default, so no extra system setup (compiler or BLAS) is required, and PyMC can
+be installed with `pip`.
 
-Once you have installed one of the above, PyMC can be installed into a new conda environment as follows:
+We also recommend installing [nutpie](https://github.com/pymc-devs/nutpie), a
+fast NUTS sampler written in Rust. When nutpie is installed, PyMC selects it as
+the default NUTS sampler automatically — typically about 2x faster than PyMC's
+built-in NUTS:
 
 ```console
-conda create -c conda-forge -n pymc_env "pymc>=5"
+pip install "pymc[nutpie]"
+```
+
+To install PyMC on its own:
+
+```console
+pip install pymc
+```
+
+## Installing with conda
+
+As an alternative, PyMC can be installed with `conda` using
+[Anaconda](https://www.anaconda.com/) or
+[Miniforge](https://github.com/conda-forge/miniforge). We recommend a fresh
+conda environment:
+
+```console
+conda create -c conda-forge -n pymc_env pymc
 conda activate pymc_env
 ```
+
 If you like, replace the name `pymc_env` with whatever environment name you prefer.
 
+To enable nutpie when using conda:
+
+```console
+conda install -c conda-forge nutpie
+```
+
 :::{seealso}
 The [conda-forge tips & tricks](https://conda-forge.org/docs/user/tipsandtricks.html#using-multiple-channels) page to avoid installation
 issues when using multiple conda channels (e.g. defaults and conda-forge).
@@ -22,20 +51,11 @@ If you wish to enable sampling using the JAX backend via NumPyro,
 you need to install it manually as it is an optional dependency:
 
 ```console
-conda install numpyro
-```
-
-Similarly, to use BlackJAX sampler instead:
-
-```console
-conda install blackjax
+pip install numpyro
 ```
 
-## Nutpie sampling
-
-You can also enable sampling with [nutpie](https://github.com/pymc-devs/nutpie).
-Nutpie uses numba as the compiler and a sampler written in Rust for faster performance.
+Similarly, to use the BlackJAX sampler instead:
 
 ```console
-conda install -c conda-forge nutpie
+pip install blackjax
 ```