Doc typo: mismatched backticks for mmsegmentation in detection/README.md

Hi, there seems to be a small formatting typo in `detection/README.md` under the Installation section.

Current line:
- Install `timm`, `mmcv-full` and \`mmsegmentation':

Suggested fix:
- Install `timm`, `mmcv-full` and `mmsegmentation`:

This fixes the backtick/quote mismatch and renders correctly in Markdown. Thanks!