Fix Readme "Installing the chart" section #180

Expected Behavior

"Installing the chart" section on readme.md in both
promitor-agent-resource-discovery
https://github.com/promitor/charts/blob/main/promitor-agent-resource-discovery/README.md#installing-the-chart

and promitor-agent-scraper
https://github.com/promitor/charts/blob/main/promitor-agent-scraper/README.md#installing-the-chart

should show --set azureAuthentication.mode='ServicePrincipal'

Actual Behavior

Is showing:
--set azureAuthentication.identity.mode='ServicePrincipal'

Bad:
azureAuthentication.identity.mode

Good:
azureAuthentication.mode

Steps to Reproduce the Problem

Open any of both readme.md