Pipe install script directly to sh (#1110)

This pipes the install from source script on Linux directly to `sh`.

Author: ldennington

docs/install.md

@@ -125,8 +125,7 @@ to install it.
 Download and run the script:
 
 ```shell
-curl -LO https://aka.ms/gcm/linux-install-source.sh &&
-sh ./linux-install-source.sh &&
+curl -L https://aka.ms/gcm/linux-install-source.sh | sh
 git-credential-manager-core configure
 ```