[tcp/udp] Improve syslog parsing description

[taylor-swanson]

What does this PR do?

• Clarified description text to include RFC 3164 and 5424 as supported formats

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.

Related issues

• Closes [tcp/udp] Improve description for syslog parsing #3731

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• Start Time: 2022-07-18T14:00:27.022+0000

• Duration: 19 min 42 sec

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Passed	9
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Total	9

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (0/0)	💚
Files	100.0% (0/0)	💚 3.043
Classes	100.0% (0/0)	💚 3.043
Methods	100.0% (6/6)	💚 10.92
Lines	100.0% (0/0)	💚 9.827
Conditionals	100.0% (0/0)	💚