[Microsoft SQL Server]: Update documentation and grok error codes

[tehbooom]

Integration Name

Microsoft SQL Server [microsoft_sqlserver]

Dataset Name

log

Integration Version

2.9.4

Agent Version

8.17.2

OS Version and Architecture

Windows Server

User Goal

Update the documentation for the integration to highlight that you may need to set the encoding to utf-16le-bom

Also, grok error codes from messages to ECS mapping.
Example: Error: %{NUMBER:event.code}, Severity: %{NUMBER:event.severity}, State: %{NUMBER:microsoft_sqlserver.state}

Existing Features

We added the encoding variable but many users do not realize to set it. Also, we grab the message but do not do additional mappings on certain events that can be further mapped like error codes.

What did you see?

User ran into an issue related to not setting the encoding. Also, user wanted to get specific error codes from log message. Needed to add extra processor to @custom pipeline to get mappings using grok.

Anything else?

No response