fix document issue

remove redundancy code

replace F with FALSE for style consistency

replace T with TRUE for style consistency

fix plot_donut issue in trans_abund

fix order_x length issue in trans_alpha

add example in subset_network

add sample_name_each param in subset_network

update document of cal_cor in trans_env

drop unused factor levels in sample_table of microtable

fix env scope bug in cal_ordination of trans_env

opt document in trans_diff

delete useless format in tidy_taxonomy func

add add_prefix param in tidy_taxonomy func

update return document in trans_diff