Add a sample config for Mistral's Vibe agent config (#194)

Note: There seems to be some nascent work on
https://github.com/mistralai/mistral-vibe to make it easier to pass
environment variables into the config and eliminate hardcoding. But,
it hasn't landed yet, as far as I can tell.

Reviewed-on: https://gitea.com/gitea/gitea-mcp/pulls/194
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Jason <jro@codegrinder.com>
Co-committed-by: Jason <jro@codegrinder.com>

README.md

@@ -15,6 +15,7 @@
   - [🚧 Installation](#-installation)
     - [Usage with Claude Code](#usage-with-claude-code)
     - [Usage with VS Code](#usage-with-vs-code)
+    - [Usage with Mistral Vibe](#usage-with-mistral-vibe)
     - [📥 Download the official binary release](#-download-the-official-binary-release)
     - [🔧 Build from Source](#-build-from-source)
     - [📁 Add to PATH](#-add-to-path)
@@ -85,6 +86,31 @@ Optionally, you can add it to a file called `.vscode/mcp.json` in your workspace
 }
 ```
 
+### Usage with Mistral Vibe
+
+Add the following configuration to your Mistral Vibe MCP configuration file (`~/.vibe/config.toml`):
+
+```toml
+[[mcp_servers]]
+name = "gitea"
+transport = "stdio"
+command = "docker"
+args = [
+    "run",
+    "--rm",
+    "-i",
+    "-e",
+    "GITEA_ACCESS_TOKEN",
+    "-e",
+    "GITEA_HOST",
+    "docker.gitea.com/gitea-mcp-server",
+]
+
+[mcp_servers.env]
+GITEA_ACCESS_TOKEN = "TOKEN"
+GITEA_HOST = "https://gitea.com"
+```
+
 ### 📥 Download the official binary release
 
 You can download the official release from [official Gitea MCP binary releases](https://gitea.com/gitea/gitea-mcp/releases).