[Azure Logs] Remove extra overview heading

[zmoog]

What does this PR do?

Remove the 'Overview' heading at the doc beginning.

TIL that https://docs.elastic.co/integrations/azure automatically adds one on its own, so we should omit it in the source code to avoid duplicates.

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.

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• Start Time: 2022-10-05T07:03:40.961+0000

• Duration: 13 min 28 sec

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Test	Results
Failed	0
Passed	123
Skipped	0
Total	123

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🚀 Benchmarks report

Package azure 👍(1) 💚(1) 💔(8)

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Data stream	Previous EPS	New EPS	Diff (%)	Result
springcloudlogs	3875.97	1980.2	-1895.77 (-48.91%)	💔
activitylogs	1312.34	622.28	-690.06 (-52.58%)	💔
application_gateway	2288.33	1477.1	-811.23 (-35.45%)	💔
auditlogs	1996.01	1396.65	-599.36 (-30.03%)	💔
firewall_logs	1980.2	1402.52	-577.68 (-29.17%)	💔
identity_protection	4237.29	2053.39	-2183.9 (-51.54%)	💔
platformlogs	3937.01	2386.63	-1550.38 (-39.38%)	💔
signinlogs	1980.2	967.12	-1013.08 (-51.16%)	💔

To see the full report comment with /test benchmark fullreport

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (10/10)	💚
Files	86.364% (19/22)	❕
Classes	86.364% (19/22)	❕
Methods	83.422% (156/187)	❕
Lines	85.011% (2779/3269)	❕
Conditionals	100.0% (0/0)	💚