Remove npm installation section per review feedback

npm package is not published yet — only show install-from-source.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

docs/getting-started/deepl-cli.mdx

@@ -11,14 +11,6 @@ The DeepL CLI is open-source under the [MIT License](https://github.com/DeepLcom
 
 ## Installation
 
-### From npm (coming soon)
-
-```bash
-npm install -g deepl-cli
-```
-
-### From source
-
 ```bash
 git clone https://github.com/DeepLcom/deepl-cli.git
 cd deepl-cli