docs: remove 2 obsolete lines

Author: Titus-von-Koeller

docs/source/installation.mdx

@@ -306,9 +306,6 @@ pip install --force-reinstall 'https://github.com/bitsandbytes-foundation/bitsan
 bitsandbytes is fully supported from ROCm 6.1 onwards (currently in alpha release).
 
 ```bash
-# Please install from source if your configuration doesn't match with these)
-pip install bitsandbytes
-
 # Install bitsandbytes from source
 # Clone bitsandbytes repo, ROCm backend is currently enabled on multi-backend-refactor branch
 git clone --depth 1 -b multi-backend-refactor https://github.com/bitsandbytes-foundation/bitsandbytes.git && cd bitsandbytes/