[WIP][SQL][DOC] Fix incorrect `code` tag

## What changes were proposed in this pull request?
This PR is to fix incorrect `code` tag in `sql-programming-guide.md`

## How was this patch tested?
Manually.

Author: Weiqing Yang <yangweiqing001@gmail.com>

Closes #15941 from weiqingy/fixtag.

(cherry picked from commit f4a98e42)
Signed-off-by: Sean Owen <sowen@cloudera.com>