add llama-completion to completion-bash executables (#17976)

Author: CISC

common/arg.cpp

@@ -639,6 +639,7 @@ static void common_params_print_completion(common_params_context & ctx_arg){
 "llama-batched-bench",
 "llama-bench",
 "llama-cli",
+"llama-completion",
 "llama-convert-llama2c-to-ggml",
 "llama-cvector-generator",
 "llama-embedding",