[CI] cSpell word normalization should merge repeated cSpell lists

[chalin]

Notice the two cSpell:ignore entries in the front matter of the quick start:

opentelemetry.io/content/en/docs/collector/quick-start.md

Lines 1 to 8 in 57120f5

	---
	title: Quick start
	cSpell:ignore: docker dokey dpkg okey telemetrygen
	description: Setup and collect telemetry in minutes!
	aliases: [getting-started]
	weight: 1
	cSpell:ignore: gobin
	---

The cSpell word normalization script should either merge these lists or report an issue.

(Found this while working on #5758.)