fix(bug): create /usr/local/bin if not present (#614)

* create /usr/local/bin if installer does not have that directory in unix install script

* minor readme updates

README.md

@@ -99,11 +99,12 @@ Group=root
 
 Restart Stanza: `sudo systemctl restart stanza`.
 
-### Linux / Macos Script
+### Linux / macOS Script
 
 - Single command install, requires the `curl` command
 - Stanza will automatically be running as a service
 - On Linux, Stanza will be running as the `root` user. On Macos, Stanza will be running as your current user.
+- `sudo` is always required for Linux installations while macOS requires it if the invoking user does not have write permissions to `/usr/local/bin`.
 
 ```shell
 sh -c "$(curl -fsSlL https://github.com/observiq/stanza/releases/latest/download/unix-install.sh)" unix-install.sh

scripts/unix-install.sh

@@ -481,9 +481,13 @@ install_package()
 
   info "Setting permissions..."
   chmod +x "$agent_binary"
-  ln -sf "$agent_binary" "/usr/local/bin/$BINARY_NAME"
   succeeded
 
+  info "Linking binary $agent_binary => /usr/local/bin/$BINARY_NAME"
+  mkdir -p /usr/local/bin
+  ln -sf "$agent_binary" "/usr/local/bin/$BINARY_NAME"
+  succeeded  
+
   info "Downloading plugins..."
   mkdir -p "$agent_home/tmp"
   curl -L "$plugins_download_url" -o "$agent_home/tmp/plugins.tar.gz" --progress-bar --fail || error_exit "$LINENO" "Failed to download plugins"