Update nshead_service.md

timer_thread: remove redundant code

fix redis args

fix heap overflow in simple_data_pool

update from apache-brpc

fix display problem in docs/cn/bvar_c++.md

It seems that "<>" will be recognized as an html tag and
cannot be displayed on web page.

limit minimum value of max_concurrency for auto_cl

fix some typos

ignore ELIMIT for circuit breaker

replace_include_with_find_package

fix grpc ut