zsh: add config files

zsh/plugin.zsh

@@ -0,0 +1,29 @@
+# Prepare for plugin init
+source $zsh_dir/zplug/init.zsh
+
+### BEGIN PLUGIN LIST ##########################################################
+
+# Syntax highlighting
+zplug "zsh-users/zsh-syntax-highlighting", defer:2
+
+# Command suggestions
+zplug "zsh-users/zsh-autosuggestions"
+
+# History search
+zplug "zsh-users/zsh-history-substring-search"
+
+# Jump to recent directories
+zplug "agkozak/zsh-z"
+
+### END PLUGIN LIST ############################################################
+
+# Finalise plugin init
+if ! zplug check --verbose; then
+    printf "Install? [y/N]: "
+    if read -q; then
+        echo; zplug install
+    fi
+fi
+
+# Then, source plugins and add commands to $PATH
+zplug load