Format vector-db.md into a table

[sneha-afk]

As proposed in #29, vector-db.md is now in a table format to match up with other files. There is a blank column left for when the Java implementation of memory connectors is available.

I also spotted an sentence where spaces were not present after commas.

Thanks!

[learn-build-service-prod[bot]]

Learn Build status updates of commit c7be7f0:

:bulb: Validation status: suggestions

File	Status	Preview URL	Details
semantic-kernel/get-started/supported-languages.md	:bulb:Suggestion		Details
semantic-kernel/memories/vector-db.md	:bulb:Suggestion		Details

semantic-kernel/get-started/supported-languages.md

• Line 73, Column 2: [Suggestion: column-header-missing - See documentation] Column headers are required for tables. Add appropriate header text, or remove any extra table cells that cause an extra column.

semantic-kernel/memories/vector-db.md

• Line 46, Column 2: [Suggestion: column-header-missing - See documentation] Column headers are required for tables. Add appropriate header text, or remove any extra table cells that cause an extra column.

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[matthewbolanos]

Thanks! Will merge it in now :)