Add missing quote in README.md
Add missing quote in README.md

Fixes #2935.

prettier/prettier,existentialism/prettier,azz/prettier,azz/prettier,existentialism/prettier,rattrayalex/prettier,azz/prettier,existentialism/prettier,prettier/prettier,azz/prettier,rattrayalex/prettier,rattrayalex/prettier,existentialism/prettier,prettier/prettier,prettier/prettier,jlongster/prettier