docs: audit and make documentation for command SELECT

[bagmeg]

This Pull Request fixes #812

Changes

• add Syntax section
• make Parameters section to table
• make Return Value section to table
• fix 127.0.0.1:6379 to 127.0.0.1:7379

[JyotinderSingh]

As of today, we do not support multiple databases inside DiceDB. Therefore SELECT is only present as a placeholder. You can add a note at the top that the SELECT method is a dummy method (which does not have any effect on the database) since DiceDB does not support multiple DBs.

[bagmeg]

As of today, we do not support multiple databases inside DiceDB. Therefore SELECT is only present as a placeholder. You can add a note at the top that the SELECT method is a dummy method (which does not have any effect on the database) since DiceDB does not support multiple DBs.

thanks for the comment, added notes to SELECT command to indicate that is now a dummy command.