add a guide page that demonstrates the simple process of migrating from `@solana/kit` to `gill` we already have a [gill vs @solana/kit comparison guide](https://gill.site/docs/compare/kit), but its not the same as a migration guide
add a guide page that demonstrates the simple process of migrating from
@solana/kittogillwe already have a gill vs @solana/kit comparison guide, but its not the same as a migration guide