Pull Request Overview

This PR enriches the DomCrawler documentation by expanding method descriptions with more detail and adding references to related components and resources.

• Expanded explanations for common Crawler methods to clarify their behavior and usage.
• Added a link to Symfony’s CSS Selector component documentation.
• Introduced an external reference for “XPath expression.”

We should probably also make it clear which methods are meant to be called on a single-node Crawler because they ignore other nodes than the first one (any method where the implementation rely on using$this->getNode(0) basically).

We have several places guaranteed to be dealing with single-node crawlers in the API:

• the callback ofeach
• the callback ofreduce
• the return value ofeq (and its shortcut) for a valid position (for an invalid position, it will be an empty crawler for which those methods relying on the first node will throw an exception)