docs: move fully typed clients into Features as the v3 headliner

Closes the long-standing #21 / #481 type-annotation requests and is the
headline change of v3 in the upgrade guide — fits Features better than
Refactor.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: vdusek

CHANGELOG.md

@@ -9,14 +9,14 @@ All notable changes to this project will be documented in this file.
 
 ### 🚀 Features
 
-- Make HTTP client pluggable with abstract base classes ([#641](https://github.com/apify/apify-client-python/pull/641)) ([5ae33a0](https://github.com/apify/apify-client-python/commit/5ae33a0a801fdacd0c456a8630fea053f9df6550)) by [@vdusek](https://github.com/vdusek), closes [#416](https://github.com/apify/apify-client-python/issues/416)
+- [**breaking**] Introduce fully typed clients ([#604](https://github.com/apify/apify-client-python/pull/604)) ([81ee194](https://github.com/apify/apify-client-python/commit/81ee1943b400b49797868fe4dfa52d1662e09370)) by [@vdusek](https://github.com/vdusek), closes [#21](https://github.com/apify/apify-client-python/issues/21), [#481](https://github.com/apify/apify-client-python/issues/481)
 - [**breaking**] Introduce tiered timeout system with per-endpoint configuration ([#653](https://github.com/apify/apify-client-python/pull/653)) ([723ec6e](https://github.com/apify/apify-client-python/commit/723ec6e5954474767a5ecbf4902d9b62f7d214f8)) by [@vdusek](https://github.com/vdusek)
+- Make HTTP client pluggable with abstract base classes ([#641](https://github.com/apify/apify-client-python/pull/641)) ([5ae33a0](https://github.com/apify/apify-client-python/commit/5ae33a0a801fdacd0c456a8630fea053f9df6550)) by [@vdusek](https://github.com/vdusek), closes [#416](https://github.com/apify/apify-client-python/issues/416)
 - Accept Pydantic models as alternatives to dicts in resource client methods ([#663](https://github.com/apify/apify-client-python/pull/663)) ([b778c20](https://github.com/apify/apify-client-python/commit/b778c2040228ff9f5a97765de10535cec3f0353e)) by [@vdusek](https://github.com/vdusek), closes [#421](https://github.com/apify/apify-client-python/issues/421)
 - Add ownership parameter to storage collection listing methods ([#696](https://github.com/apify/apify-client-python/pull/696)) ([51a92a3](https://github.com/apify/apify-client-python/commit/51a92a31dac5dd433acfaea76155011d0892d8c8)) by [@nmanerikar](https://github.com/nmanerikar)
 
 ### 🚜 Refactor
 
-- [**breaking**] Introduce fully typed clients ([#604](https://github.com/apify/apify-client-python/pull/604)) ([81ee194](https://github.com/apify/apify-client-python/commit/81ee1943b400b49797868fe4dfa52d1662e09370)) by [@vdusek](https://github.com/vdusek), closes [#21](https://github.com/apify/apify-client-python/issues/21), [#481](https://github.com/apify/apify-client-python/issues/481)
 - [**breaking**] Update default timeout tiers on non-storage resource clients ([#664](https://github.com/apify/apify-client-python/pull/664)) ([0b35bbe](https://github.com/apify/apify-client-python/commit/0b35bbe212a8a64c5aea5d5d813315252760b055)) by [@vdusek](https://github.com/vdusek)
 - [**breaking**] Use snake case for `actors().list(sort_by=...)` ([#736](https://github.com/apify/apify-client-python/pull/736)) ([eb70b64](https://github.com/apify/apify-client-python/commit/eb70b64eac86faba5cbe943845ad144ec0277896)) by [@vdusek](https://github.com/vdusek), closes [#700](https://github.com/apify/apify-client-python/issues/700)