docs: Revert documentation restructure (#763)

## Summary

This PR reverts commit 89c0358 which restructured the documentation by
splitting the overview page into three separate pages.

## Changes

- Restores the original single overview page structure
- Moves the webserver guide back from guides to concepts section
- Renumbers concept pages back to their original order
- Removes the separate introduction and installation pages

## Reason for revert

[Add reason here]

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Author: patrikbraborec

README.md

@@ -159,7 +159,7 @@ To create and run Actors through Apify Console,
 see the [Console documentation](https://docs.apify.com/academy/getting-started/creating-actors#choose-your-template).
 
 To create and run Python Actors locally, check the documentation for
-[how to create and run Python Actors locally](https://docs.apify.com/sdk/python/docs/quick-start).
+[how to create and run Python Actors locally](https://docs.apify.com/sdk/python/docs/overview/running-locally).
 
 ## Guides
 

docs/01_introduction/index.mdx

@@ -1,18 +1,47 @@
 ---
-title: Quick start
-sidebar_label: Quick start
-description: 'Get started with the Apify SDK for Python by creating your first Actor and learning the basics.'
----
-
-Learn how to create and run Actors using the Apify SDK for Python.
-
+title: Overview
+sidebar_label: Overview
 ---
 
 import Tabs from '@theme/Tabs';
 import TabItem from '@theme/TabItem';
 import CodeBlock from '@theme/CodeBlock';
 
-## Step 1: Creating Actors
+The Apify SDK for Python is the official library for creating [Apify Actors](https://docs.apify.com/platform/actors) in Python.
+
+```py
+from apify import Actor
+from bs4 import BeautifulSoup
+import requests
+
+async def main():
+    async with Actor:
+        input = await Actor.get_input()
+        response = requests.get(input['url'])
+        soup = BeautifulSoup(response.content, 'html.parser')
+        await Actor.push_data({ 'url': input['url'], 'title': soup.title.string })
+```
+
+## Requirements
+
+The Apify SDK requires Python version 3.10 or above to run Python Actors locally.
+
+## Installation
+
+The Apify Python SDK is available as [`apify`](https://pypi.org/project/apify/) package on PyPi. To install it, run:
+
+```bash
+pip install apify
+```
+
+When you create an Actor using the Apify CLI, the Apify SDK for Python is installed for you automatically.
+
+If you are not developing Apify Actors and you just need to access the Apify API from Python,
+consider using the [Apify API client for Python](/api/client/python) directly.
+
+## Quick start
+
+### Creating Actors
 
 To create and run Actors in Apify Console, refer to the [Console documentation](/platform/actors/development/quick-start/web-ide).
 
@@ -26,9 +55,9 @@ apify create my-first-actor --template python-start
 
 This will create a new folder called `my-first-actor`, download and extract the "Getting started with Python" Actor template there, create a virtual environment in `my-first-actor/.venv`, and install the Actor dependencies in it.
 
-![actor create command run](./images/apify-create.gif)
+![actor create command run](../01_overview/images/apify-create.gif)
 
-## Step 2: Running the Actor
+#### Running the Actor
 
 To run the Actor, you can use the [`apify run` command](/cli/docs/reference#apify-run):
 
@@ -45,7 +74,7 @@ This command:
 
 The Actor input, for example, will be in `storage/key_value_stores/default/INPUT.json`.
 
-## Step 3: Understanding Actor structure
+## Actor structure
 
 All Python Actor templates follow the same structure.
 
@@ -93,6 +122,31 @@ asyncio.run(main())`
 If you want to modify the Actor structure, you need to make sure that your Actor is executable as a module, via `python -m src`, as that is the command started by `apify run` in the Apify CLI.
 We recommend keeping the entrypoint for the Actor in the `src/__main__.py` file.
 
+## Adding dependencies
+
+First, add the dependencies in the [`requirements.txt`](https://pip.pypa.io/en/stable/reference/requirements-file-format/) file in the Actor source folder.
+
+Then activate the virtual environment in `.venv`:
+
+<Tabs groupId="operating-systems">
+    <TabItem value="unix" label="Linux / macOS" default>
+        <CodeBlock language="bash">{
+`source .venv/bin/activate`
+        }</CodeBlock>
+    </TabItem>
+    <TabItem value="win" label="Windows">
+        <CodeBlock language="powershell">{
+`.venv\\Scripts\\activate`
+        }</CodeBlock>
+    </TabItem>
+</Tabs>
+
+Finally, install the dependencies:
+
+```bash
+python -m pip install -r requirements.txt
+```
+
 ## Next steps
 
 ### Guides