One of the links is to Google’s Sight Reliability Workbook (https://sre.google/workbook/table-of-contents/). At my last company, we implemented SLOs based on the advice in this workbook, and I thought it was an excellent approach. Having internal reliability targets that directly map to the meaningful parts of the customer experience, and setting up dashboards and alerts based on these targets, is a very powerful approach to achieving reliability that matters for users.
A great doc from Google that they didn’t link to above is “My Philosophy on Alerting”, by Rob Ewaschuk (https://docs.google.com/document/d/199PqyG3UsyXlwieHaqbGiWVa...). A must read for anyone setting up alerts IMO.