docusaurus pain fixes
speed up 2hr+ SSG build times for large sites!
switch jsloader to esbuilder instead of weback inside docusaurus.config.js
don't delete node_modules/.cache - ie via docusaurs clear - unless serious bugs prevent build - it is used to speed up repeat builds
set DOCUSAURUS_SSR_CONCURRENCY=5 in .env - depending on PC - lower concurrency setting may lower build freeze and memory spike