A missing "of"

[FakhriAz]

AppFlowy-Docs/blog-highlights/demystifying-appflowy-editors-codebase.md

Line 718 in f3bd77d

// if current selection consists an occurrence of matched pattern.

This "consists an occurrence" would rather be "consists of an occurrence"

[Xazin]

Seems to be also missing the, as in if the current selection.

[FakhriAz]

I found many missing the when checking the Docs, I was not sure if I should create issues regarding them. I thought start with the most obvious ones.