[2.0] docs: remove the word "BOM"

[jkowalleck]

CycloneDX is no longer BOM-only.
lets remove if from all the docs

still using "BOM"

• specification/schema/2.0/cyclonedx-2.0.schema.json

  Lines 34 to 37 in a1c8aeb

  	"serialNumber": {
  	"type": "string",
  	"title": "BOM Serial Number",
  	"description": "Every BOM generated SHOULD have a unique serial number, even if the contents of the BOM have not changed over time. If specified, the serial number must conform to [RFC 4122](https://www.ietf.org/rfc/rfc4122.html). Use of serial numbers is recommended.",

• to be continued