docs: Mention pixi and conda in installation methods (#398)

Summary:
pyrefly is also available on conda-forge: https://prefix.dev/channels/conda-forge/packages/pyrefly, https://github.com/conda-forge/pyrefly-feedstock

Pull Request resolved: #398

Reviewed By: rchen152

Differential Revision: D75693787

Pulled By: connernilsen

fbshipit-source-id: 1460aac67547404f6ee3e61bf134d50f9f3f598d

Author: pavelzw

website/docs/installation.mdx

@@ -7,7 +7,7 @@ Pyrefly is available on [Pypi](https://pypi.org/project/pyrefly/) with a new rel
 
 ## Install
 
-You can use `uv`, `poetry`, or `pip` to install the package if you want to experiment with our tool.
+You can use `uv`, `poetry`, `pip`, `pixi` or `conda` to install the package if you want to experiment with our tool.
 
 Simply `cd` into your project directory and run:
 
@@ -36,6 +36,22 @@ pyrefly init
 pyrefly check
 ```
 
+### Using Pixi
+
+```
+pixi add pyrefly
+pixi run pyrefly init
+pixi run pyrefly check
+```
+
+### Using Conda
+
+```
+conda install -c conda-forge pyrefly
+pyrefly init
+pyrefly check
+```
+
 ## Configure
 
 Set up a basic configuration file to type-check your project. You can add configuration options to a `pyproject.toml` file or create a `pyrefly.toml` file in your project directory. All [configuration options are documented here](../configuration).