Update docs about sprintf vs GlSprintf usage

What does this MR do?

Update docs about sprintf vs GlSprintf usage

Also:

• Fix a broken link to the GlSprintf documentation page.
• Pass false as the third argument to sprintf in the JS-without-Vue examples which interpolate HTML. Without this argument, the examples won't work as expected.

Screenshots (strongly suggested)

n/a

Does this MR meet the acceptance criteria?

Conformity

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  • I have included a changelog entry.
  • I have not included a changelog entry because docs-only.
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