Remove free credit mentions from documentation (#4322)

## Summary
Updated documentation to remove references to free credits and
promotional offers, simplifying the API key setup instructions across
multiple documentation files.

## Key Changes
- Removed "$10 free credits" mention from the ChatBrowserUse
recommendation in AGENTS.md
- Simplified the API key acquisition language from "Don't have one? We
give you **$10** to try it out" to "Get your API key"
- Updated the .env file comment from "Get 10$ of free credits" to "Get
your API key"
- Removed the free credits reference from the README.md quick start
section

## Details
These changes streamline the documentation by removing time-sensitive
promotional information, making the setup instructions more evergreen
and focused on the core functionality rather than temporary offers. The
links to the API key generation page remain unchanged.

https://claude.ai/code/session_01CTCYfXrPi3SxEZeBy9DevS

<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Removed all $10 signup credit mentions from `AGENTS.md` and `README.md`
and simplified API key setup wording. Updated `ChatBrowserUse` callouts
and `.env` comments to link to the API key page without promotions.

<sup>Written for commit eb17dac289.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

AGENTS.md

@@ -36,7 +36,7 @@ uv sync
 To get started with Browser Use you need to install the package and create an `.env` file with your API key.
 
 <Note icon="key" color="#FFC107" iconType="regular">
-  `ChatBrowserUse` offers the [fastest and most cost-effective models](https://browser-use.com/posts/speed-matters/), completing tasks 3-5x faster. Get started with \$10 of [free LLM credits](https://cloud.browser-use.com/new-api-key).
+  `ChatBrowserUse` offers the [fastest and most cost-effective models](https://browser-use.com/posts/speed-matters/), completing tasks 3-5x faster. Get your API key at [cloud.browser-use.com](https://cloud.browser-use.com/new-api-key).
 </Note>
 
 ## 1. Installing Browser-Use
@@ -61,7 +61,7 @@ uvx browser-use install
 Create a `.env` file and add your API key.
 
 <Callout icon="key" iconType="regular">
-  We recommend using ChatBrowserUse which is optimized for browser automation tasks (highest accuracy + fastest speed + lowest token cost). Don't have one? We give you **\$10** to try it out [here](https://cloud.browser-use.com/new-api-key).
+  We recommend using ChatBrowserUse which is optimized for browser automation tasks (highest accuracy + fastest speed + lowest token cost). Get your API key [here](https://cloud.browser-use.com/new-api-key).
 </Callout>
 
 ```bash .env theme={null}
@@ -76,7 +76,7 @@ Then add your API key to the file.
   ```bash Browser Use theme={null}
   # add your key to .env file
   BROWSER_USE_API_KEY=
-  # Get 10$ of free credits at https://cloud.browser-use.com/new-api-key
+  # Get your API key at https://cloud.browser-use.com/new-api-key
   ```
 
   ```bash Google theme={null}

README.md

@@ -55,7 +55,7 @@ uv init && uv add browser-use && uv sync
 # uvx browser-use install  # Run if you don't have Chromium installed
 ```
 
-**2. [Optional] Get your API key from [Browser Use Cloud](https://cloud.browser-use.com/new-api-key) (new signups get $10 free credits):**
+**2. [Optional] Get your API key from [Browser Use Cloud](https://cloud.browser-use.com/new-api-key):**
 ```
 # .env
 BROWSER_USE_API_KEY=your-key