Update README.md: Fix grep in macOS instructions (#891)

The current command has a slightly broken pattern, and fails to find `gtp_example.cfg`.

README.md

@@ -77,7 +77,7 @@ KataGo currently officially supports both Windows and Linux, with [precompiled e
 ### MacOS
 The community also provides KataGo packages for [Homebrew](https://brew.sh) on MacOS - releases there may lag behind official releases slightly.
 
-Use `brew install katago`. The latest config files and networks are installed in KataGo's `share` directory. Find them via `brew list --verbose katago`. A basic way to run katago will be `katago gtp -config $(brew list --verbose katago | grep gtp*.cfg) -model $(brew list --verbose katago | grep .gz | head -1)`. You should choose the Network according to the release notes here and customize the provided example config as with every other way of installing KataGo.
+Use `brew install katago`. The latest config files and networks are installed in KataGo's `share` directory. Find them via `brew list --verbose katago`. A basic way to run katago will be `katago gtp -config $(brew list --verbose katago | grep 'gtp.*\.cfg') -model $(brew list --verbose katago | grep .gz | head -1)`. You should choose the Network according to the release notes here and customize the provided example config as with every other way of installing KataGo.
 
 ### OpenCL vs CUDA vs TensorRT vs Eigen
 KataGo has four backends, OpenCL (GPU), CUDA (GPU), TensorRT (GPU), and Eigen (CPU).