Document semgrep support for golang

What does this MR do and why?

Describe in detail what your merge request does and why.

In %14.4 we added golang support to our semgrep analyzer. This MR adds this support to our user documentation for SAST.

• Tracking issue: #339865 (closed)
• Analyzer release issue: https://gitlab.com/gitlab-org/security-products/release/-/issues/115
• MR adding support to the analyzer: gitlab-org/security-products/analyzers/semgrep!76 (merged)
• MR adding detection rules to the SAST vendored template: !70704 (merged)

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