Add incremental analysis documentation for the CodeQL CLI

[coadaflorin]

Summary

This PR adds a new article to the "Scan from the command line" section covering incremental analysis with the CodeQL CLI. The article documents two complementary features for speeding up CodeQL analysis on pull requests:

• Diff-informed analysis — restricts query results to alerts within the PR diff, making analysis faster and more focused.
• Overlay analysis — builds on a cached base database from the default branch instead of creating a full database from scratch, dramatically reducing database creation and query evaluation time.

Changes

• New file: content/code-security/.../scan-from-the-command-line/incremental-analysis.md — comprehensive how-to guide covering both features with step-by-step instructions, CLI flags, requirements, and a decision matrix.
• Updated: index.md — added the new article to the children list.

Source

Content adapted from the internal CI integrator guide at github/semmle-code (documentation/markdown-internal/incremental-codeql-ci.md), rewritten to match the GitHub Docs style and conventions.

Article structure

1. About incremental analysis — overview of both features
2. Diff-informed analysis — concept, step-by-step guide (determine diff → parse ranges → create extension pack → run queries → filter SARIF), CLI flags summary
3. Overlay analysis — concept, requirements, overlay-base mode (default branch), overlay mode (PRs), CLI flags summary, minimum CLI versions
4. Using both features together — decision matrix for different scenarios

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Source	Review	Production	What Changed
New file: code-security/how-tos/find-and-fix-code-vulnerabilities/scan-from-the-command-line/incremental-analysis.md	fpt ghec ghes@ 3.21 3.20 3.19 3.18 3.17 3.16	fpt ghec ghes@ 3.21 3.20 3.19 3.18 3.17 3.16
code-security/how-tos/find-and-fix-code-vulnerabilities/scan-from-the-command-line/index.md	fpt ghec ghes@ 3.21 3.20 3.19 3.18 3.17 3.16	fpt ghec ghes@ 3.21 3.20 3.19 3.18 3.17 3.16

Key: fpt: Free, Pro, Team; ghec: GitHub Enterprise Cloud; ghes: GitHub Enterprise Server

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[Copilot]

Pull request overview

Adds a new “Incremental analysis” how-to under the CodeQL CLI “Scan from the command line” section, documenting diff-informed analysis and overlay analysis to speed up pull request scanning workflows.

Changes:

• Added a new article describing diff-informed analysis (diff range extension pack + SARIF filtering) and overlay analysis (overlay-base + overlay mode).
• Updated the section index to include the new incremental analysis article.

Show a summary per file

File	Description
content/code-security/how-tos/find-and-fix-code-vulnerabilities/scan-from-the-command-line/index.md	Adds the new incremental analysis page to the navigation children list.
content/code-security/how-tos/find-and-fix-code-vulnerabilities/scan-from-the-command-line/incremental-analysis.md	New documentation page covering incremental analysis techniques (diff-informed and overlay) with steps, flags, and guidance.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1