Create a new guide for scaling the crawlers

[vdusek]

• We could create a new documentation guide for scaling the crawlers (mainly the features from _autoscaling subpackage).
• The guide should include the following:
  • ConcurrencySettings - how users can configure the concurrency of requests.
  • Add a short explanation of the internal components:
    • Snapshotter,
    • AutoscaledPool.
• Inspiration: https://crawlee.dev/docs/guides/scaling-crawlers
• How to name it? I used "request scaling" here, but it is not precise enough.