bug: `getting started` docs for victoria-logs-* Helm charts contain incorrect and misleading information

[valyala]

Chart name and version
This concerns docs for all the VictoriaLogs-related Helm charts:

• victoria-logs-single
• victoria-logs-cluster
• victoria-logs-collector
• victoria-logs-multilevel

Describe the bug

The docs for victoria-logs-* helm charts contain getting started guides on how to quickly configure and deploy the corresponding chart with the minimum settings. Some of these guides are misleading/incorrect and/or do not contain the needed information, which may prevent from using these charts by new users. Examples:

• The docs for victoria-logs-single do not mention endpoints for logs' ingestion and querying. They also do not refer to the corresponding docs - how to send logs to VictoriaLogs and how to query logs. So, users may struggle in figuring out how to send and query logs from the just installed VictoriaLogs instance.
• The docs for victoria-logs-cluster do not mention how to send logs to the installed cluster.
• The docs for victoria-logs-collector miss the information on how to send logs to VictoriaLogs instances deployed via victoria-logs-single and victoria-logs-cluster Helm charts. This prevents from seamless setup of victoria-logs-collector.
• The docs for victoria-logs-multilevel miss working examples on how to setup global querying view over VictoriaLogs instances deployed via victoria-logs-single and victoria-logs-cluster.

Please follow all these docs as a user who doesn't know the internals of these charts, fix misleading docs and add missing information to the docs, so new users could quickly setup VictoriaLogs in Kubernetes by following these guides.

Please verify that all the commands and configs mentioned in the guides work as intended. If something doesn't work, then fix it.