docs: adds info on extending PrismaClient type in readme

[NGimbal]

Relevant Github Issue:

#129

I added this in the default integration snippet because the snippet already uses Typescript, and my experience tells me it's important. Please let me know if you'd like me to keep that block of code more minimal and I can create a separate section that talks about extending the PrismaClient type.

Thanks again for your hard work on this library!

[coveralls]

Pull Request Test Coverage Report for Build 11470422894

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 79.242%

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Totals
Change from base Build 11019901257:	0.0%
Covered Lines:	269
Relevant Lines:	320

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💛 - Coveralls

[franky47]

Thanks! Yes I think this might be a bit verbose for the initial setup phase, I'd rather have this code block focusing on showcasing the fieldEncryptionExtension function (too bad we can't highlight lines on GitHub).

suggestion: Maybe we could move the TS-specifics into a <details><summary> block, with a title of something like "Typing the extended client with TypeScript", what do you think?