Fix docs: Add missing words in understanding page

[bqrkhn]

Was going through the docs and found minor issue. The sentence did not any make sense.

This PR fixes that.

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[bqrkhn]

Should I change this:

The Open Source version uses SQLite, and soon Postgres or MySQL.

To this:

The Open Source version uses SQLite, Postgres and MySQL.

Since now convex self hosting supports that. This text is in the same database section.

[nipunn1313]

Should I change this:

The Open Source version uses SQLite, and soon Postgres or MySQL.

To this:

The Open Source version uses SQLite, Postgres and MySQL.

Since now convex self hosting supports that. This text is in the same database section.

Yeah! Go for it!

[nipunn1313]

looks good. The previous wording is colloquial (works in some contexts/dialects) - but the new wording you propose sounds broadly better.

[nipunn1313]

I'll merge this as is - you can make another PR for the other fix! Appreciate it!

[nipunn1313]

merged in https://github.com/get-convex/convex/commit/8688edbaf4b21facb4a25ac009beb45a715ed11c