Update documentation and Nedi diagrams to Mermaid 12.1 - #3133

Changed pages include:

• 404.html - view
• blog/index.html - view
• search/index.html - view
• docs/alerts-&-notifications/index.html - view
• docs/ask-nedi/index.html - view
• docs/collecting-metrics/index.html - view
• docs/dashboards-and-charts/index.html - view
• docs/developer-and-contributor-corner/index.html - view
• docs/edge-device-monitoring/index.html - view
• docs/exporting-metrics/index.html - view

There are more changes not included in the list