HTTP API: remove some show statements (#1758)

### What problem does this PR solve?

Remove show statements:
show segments;
show segment detail;
show blocks;
show blocks detail;
show block column;
show index segments;
show index segment;

### Type of change

- [x] Documentation Update

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

Author: JinHai-CN