docs: `max_requests_per_crawl` intro example differs from the JS SDK (10 vs 20)

[govarthenan]

While going through the introduction, I noticed the "Limit your crawls" section uses a different max_requests_per_crawl value than the equivalent section in the JavaScript SDK docs.

• Python — Introduction → Adding more URLs: the example uses max_requests_per_crawl=10, and the text reads "no new requests will be started after the 10th request is finished."
• JavaScript — Introduction → Adding more URLs: the same section uses maxRequestsPerCrawl: 20 and "after the 20th request is finished."

The two introductions are otherwise near-identical ports of each other, so the differing number looks incidental rather than deliberate. It's harmless, but a little confusing when cross-referencing the two SDKs while learning.

For what it's worth, on main the Python section is already internally consistent (both the code and the prose say 10) — so this isn't an internal mismatch, just a cross-SDK one.

I'm happy to open a small PR aligning the Python example to 20 to match JS. If you'd rather standardize on 10 and have the JS side change instead, just say so and I'll close this.

[vdusek]

max_requests_per_crawl=10 example is used throughout the codebase (210 occurrences across 208 files).