fix(migration guide): proofread and correct

related to #CAM-2335

Conflicts:
	site/src/documents/guides/migration-guide/chapters/20-migrate-from-fox/00-overview.html.md
	site/src/documents/guides/migration-guide/chapters/20-migrate-from-fox/30-migrate-server.html.md
	site/src/documents/guides/migration-guide/chapters/31-migrate-from-camunda-bpm-71/00-overview.html.md
	site/src/documents/guides/migration-guide/chapters/31-migrate-from-camunda-bpm-71/05-migrate-process-engine-configuration.html.md
	site/src/documents/guides/migration-guide/chapters/31-migrate-from-camunda-bpm-71/20-migrate-db.html.md
	site/src/documents/guides/migration-guide/chapters/31-migrate-from-camunda-bpm-71/40-migrate-cockpit-plugins.html.md
	site/src/documents/guides/migration-guide/chapters/40-patch-level-upgrade/00-overview.html.md