[DOCS-6870] Add OP SDS transform guide

[maycmlee]

What does this PR do? What is the motivation?

Adds new guide for OP SDS transform.

DOCS-6870

Merge instructions

• Please merge after reviewing

Additional notes

[github-actions]

Preview links (active after the build_preview check completes)

New or renamed files

• https://docs-staging.datadoghq.com/may/docs-6870/sds-transform-guide/observability_pipelines/guide/sensitive_data_scanner_transform

Modified Files

• https://docs-staging.datadoghq.com/may/docs-6870/sds-transform-guide/agent/guide/private-link

[estherk15]

Very cool! Left non-blocking suggestions!

[fuchsnj]

Overall it looks good, just some small comments

[fuchsnj]

Suggested change

	The `sensitive_data_scanner` transform supports Perl Compatible RegEx (PCRE), but the following patterns are not supported:
	The `sensitive_data_scanner` transform supports Perl Compatible RegEx (PCRE2), but the following patterns are not supported:

The supported syntax is a subset of PCRE2. I have compiled an exhaustive list of exactly what is supported if that helps here at all: https://datadoghq.atlassian.net/wiki/spaces/SDS/pages/3221292288/SDS+Regex+Syntax

Just note that the syntax listed above is what the Core SDS library supports. OPW is currently using a different implementation (which is NOT PCRE or PCRE2 compliant) but it will be switched out very soon (likely next week).

[maycmlee]

Thanks @fuchsnj, good to know! I'd like to publish this doc this week, do you think it makes sense to remove this information for now, and then add it back when OPW has switched to be PCRE2 compliant?

Also, thanks for the confluence link. At some point, it seems we should have public documentation on what regex syntax is supported? Is it usually so specific what syntax is available? Or can we point them to the regex101.com site you mention?

[fuchsnj]

I'd like to publish this doc this week, do you think it makes sense to remove this information for now, and then add it back when OPW has switched to be PCRE2 compliant?

It's probably fine to keep it as PCRE2 for now. The differences are fairly subtle and not something users are likely to notice.

At some point, it seems we should have public documentation on what regex syntax is supported?

That confluence doc is mostly for internal documentation now, and to help write any public documentation whenever that happens. I don't expect you to include the whole thing here. I expect in the future we will probably have more detailed public docs about the regex syntax in the SDS docs that you could link to here.

[maycmlee]

Perfect, thanks for the info!