[MASSEMBLY-958] Clarify dependency set resolution semantics

[wilx]

Fixes #1163.

Summary

Clarify that dependency sets are evaluated against the project's dependency
graph after Maven dependency conflict resolution, and that include patterns do
not create separate dependency-resolution roots.

Motivation

The useTransitiveDependencies and useTransitiveFiltering descriptions can
be read as if the dependencies matching a dependency set's includes are
resolved as an independent graph. In practice, Maven first mediates the
assembly project's complete dependency graph. The Assembly Plugin then applies
dependency-set filters to the surviving artifacts and dependency trails.

As a result, a direct project dependency can supersede the same artifact
reached transitively through an included dependency. The surviving direct
artifact no longer has the included dependency in its trail and is not selected
through transitive filtering.

The clarification is added to both the assembly and assembly-component model
descriptions so their generated reference documentation remains consistent.

Validation

• mvn -q verify
• Confirmed that the generated Java model and both generated XSDs contain the
  clarification.

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[elharo]

Why would anybody think they did?

[wilx]

🤷‍♂️

[Copilot]

Pull request overview

Clarifies Maven Assembly Plugin dependencySet documentation to reflect actual resolution behavior: dependency sets are filtered from the already conflict-resolved project dependency graph rather than being resolved as independent roots.

Changes:

• Updated the DependencySet model description to state it is evaluated after Maven dependency conflict resolution.
• Clarified that include patterns do not create separate dependency-resolution roots (applies to both assembly and assembly-component models).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/main/mdo/assembly.mdo	Updates DependencySet description to clarify post-conflict-resolution evaluation semantics.
src/main/mdo/assembly-component.mdo	Mirrors the same DependencySet documentation clarification for the component model to keep generated docs consistent.

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[github-actions]

@elharo Please assign appropriate label to PR according to the type of change.