[Processing] Broken links to docs-examples

For example, https://docs.ton.org/payments/jettons page references https://github.com/ton-org/docs-examples/blob/processing/guidebook/payment-processing/src/deposits/jetton-invoices.ts, but the latter is currently present on a different branch (jetton-processing-only).

Find all other such broken links and fix them. Related to #1358.