Fix zsh path autocompletion (#88)

scripts/auto-completion/zsh/_nnn

@@ -17,6 +17,6 @@ args=(
     '(-p)-p[specify custom nlay]:path to nlay'
     '(-S)-S[start in disk usage analyzer mode]'
     '(-v)-v[show program version and exit]'
-    '*: :_guard "^-*" keyword'
+    '*:filename:_files'
 )
 _arguments -S -s $args