docs(spec): align scheme_exact_algo with v2 amount and verification#1879

temptemp3 wants to merge 2 commits intocoinbase:maincoinbase/x402:mainfrom

temptemp3:docs/scheme-exact-algo-v2-verifytemptemp3/x402-pr-docs:docs/scheme-exact-algo-v2-verifyCopy head branch name to clipboard