Awkward Phrase, Article and Clarity Issues

https://github.com/AppFlowy-IO/AppFlowy-Docs/blob/cb1d8a02d240749c85bb75e37c96b9903393f235/essential-documentation/contribute-to-appflowy/write-for-appflowy/drafts/draft-how-to-add-a-new-property-to-appflowy-database.md?plain=1#L59-L61

### Awkward Phrase:
***Inaccurate:***
Now with some knowledge that how Flowy-database is structured, we can take a look at a practical example.

***Accurate:***
Now`,` with some knowledge of how `the AppFlowy` database is structured, we can take a look at a practical example.

### Article and Clarity Issue :
***Inaccurate:***
Let's first see what `is` property and then go further.

***Accurate:***
Let's first see what `a` property `is,` and then go further.