Update download command to support different architectures

installation/README.md

@@ -211,14 +211,22 @@ kubectl get pods -n fission --watch
 
 ## Fission Client
 
-### Mac & Linux
+### Mac & Linux (curl)
 
 ```shell
 OS=$(uname -s | tr '[:upper:]' '[:lower:]')
-curl -Lo fission https://github.com/fission/fission/releases/download/v$FISSION_VERSION/fission-v$FISSION_VERSION-$OS-amd64 \
+ARCH=$(uname -m | tr '[:upper:]' '[:lower:]')
+curl -Lo fission https://github.com/fission/fission/releases/download/v$FISSION_VERSION/fission-v$FISSION_VERSION-$OS-$ARCH \
    && chmod +x fission && sudo mv fission /usr/local/bin/
 ```
 
+### Mac (brew)
+
+```shell
+brew tap xxxbrian/tap
+brew install fission-cli
+```
+
 ### Windows
 
 For Windows, please use the Linux binary on WSL.