cef: clarify the scope of existing dashboards

[efd6]

What does this PR do?

The dashboards that exist were originally ArcSight dashboards and have not been
updated to work with other CEF inputs, so note in the names and descriptions that
they are for ArcSight.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• For cef: make dashboard work with CEF standard inputs #3469

Screenshots

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• Start Time: 2022-06-06T01:16:28.082+0000

• Duration: 15 min 15 sec

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Passed	84
Skipped	0
Total	84

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (3/3)	💚 3.513
Classes	100.0% (3/3)	💚 3.513
Methods	95.0% (19/20)	👍 5.495
Lines	89.286% (400/448)	👎 -1.501
Conditionals	100.0% (0/0)	💚