doc: follow new markup guideline about check command documentation
doc: follow new markup guideline about clearlock command documentation
doc: follow new markup guideline about column_remove command documentation
doc: follow new markup guideline about define_selector command documentation
doc: follow new markup guideline about defrag command documentation
doc: follow new markup guideline about dump command documentation
doc: follow new markup guideline about log_level command documentation
doc: follow new markup guideline about log_put command documentation
doc: follow new markup guideline about log_reopen command documentation
doc: follow new markup guideline about quit command documentation
doc: follow new markup guideline about register command documentation
doc: follow new markup guideline about shutdown command documentation
doc: follow new markup guideline about status command documentation
doc: follow new markup guideline about suggest command documentation
doc: follow new markup guideline about table_list command documentation
doc: follow new markup guideline about table_remove command documentation
Merge pull request #189 from naoa/reformat-command-reference

doc: follow new markup guideline about old markup command documentation

Patch by Naoya Murakami. Thanks!!!