doc: update pip installation instructions

README.md

@@ -81,7 +81,7 @@ The preferred way to run Sage on Windows is using the [Windows Subsystem for
 Linux](https://docs.microsoft.com/en-us/windows/wsl/faq), a.k.a. WSL, which allows
 you to install a standard Linux distribution such as Ubuntu within
 your Windows. Make sure you allocate WSL sufficient RAM; 5GB is known to work, while
-2GB might be not enough for building Sage from source. 
+2GB might be not enough for building Sage from source.
 Then all instructions for installation in Linux apply.
 
 As an alternative, you can also run Linux on Windows using Docker ([see
@@ -428,18 +428,18 @@ in the Installation Guide.
     or JupyterLab installation, as described in [section
     "Launching SageMath"](https://doc.sagemath.org/html/en/installation/launching.html)
     in the installation manual.
-    
+
 Alternative Installation using PyPI
 ---------------
 
 For installation of `sage` in python using `pip` you need to install `sagemath-standard`. First, activate your python virtual environment and follow these steps:
 
             $ python3 -m pip install sage_conf
             $ ls $(sage-config SAGE_SPKG_WHEELS)
-            $ python3 -m pip install $(sage-config SAGE_SPKG_WHEELS)/*.whl 
-            $ python3 -m pip install sagemath-standard
+            $ python3 -m pip install $(sage-config SAGE_SPKG_WHEELS)/*.whl sage_setup
+            $ python3 -m pip install --no-build-isolation sagemath-standard
 
-You need to install `sage_conf`, a wheelhouse of various python packages. You can list the wheels using `ls $(sage-config SAGE_SPKG_WHEELS)`. After manual installation of these wheels, you can install the sage library, `sagemath-standard`. 
+You need to install `sage_conf`, a wheelhouse of various python packages. You can list the wheels using `ls $(sage-config SAGE_SPKG_WHEELS)`. After manual installation of these wheels, you can install the sage library, `sagemath-standard`.
 
 **NOTE:** You can find `sage` and `sagemath` pip packages but with these packages, you will encounter `ModuleNotFoundError`.