docs: Add upgrade strategy to installation notes

Author: mikromyra

docs/installation.md

@@ -4,20 +4,20 @@ In most cases it should be possible to install Software Accounting as long as Py
 
 ## Virtual environment
 
-An easy opyion to install and update Software Accounting is to install it in a Python virtual environment. Create the Python virtual environment where you want it installed, and install Software Accounting using pip. Pip will install Software Accounting from the Python Packaging Index (PyPI).
+Using a Python virtual environment makes it simple to install and update Software Accounting, and its dependencies. Create the Python virtual environment where you want it installed, and install Software Accounting using pip. Pip will install Software Accounting from the Python Packaging Index (PyPI).
 
 ```
 python -m venv /opt/softwareaccounting
 /opt/softwareaccounting/bin/pip install softwareaccounting
 ```
 
-You can then update Software Accounting as new releases are published to PyPI.
+You can then update Software Accounting and its dependencies as new releases are published to PyPI.
 
 ```
-/opt/softwareaccounting/bin/pip install --upgrade softwareaccounting
+/opt/softwareaccounting/bin/pip install --upgrade --upgrade-strategy=eager softwareaccounting
 ```
 
-The POST Receiver is optional, it will not be installed by default but it can be installed with pip.
+The POST Receiver is optional, add it as an extras if needed when installing.
 
 ```
 /opt/softwareaccounting/bin/pip install 'softwareaccounting[post-receiver]'