pixi: Improve the documentation

Author: jorisv

README.md

@@ -85,7 +85,7 @@ To build **EigenPy** from source the easiest way is to use [Pixi](https://pixi.s
 
 [Pixi](https://pixi.sh/latest/) is a cross-platform package management tool for developers that
 will install all required dependencies in `.pixi` directory.
-It's used by our CI agent so you will have the guarantee to have exactly the same dependencies we use to build it.
+It's used by our CI agent so you have the guarantee to get the right dependencies.
 
 Run the following command to install dependencies, configure, build and test the project:
 
@@ -94,7 +94,7 @@ pixi run test
 ```
 
 The project will be built in the `build` directory.
-You can now run `pixi shell` and build the project with `cmake` and `ninja`.
+You can now run `pixi shell` and build the project with `cmake` and `ninja` manually.
 
 ## Credits