feat(docs): add SigNoz documentation and logo

Adds comprehensive documentation for SigNoz observability platform including:
- Service overview and description
- URL configuration for UI and Otel Collector
- Two deployment strategies (subdomain per receiver vs. port exposure)
- SMTP email configuration for invitations and alerts
- Links to official documentation

Related to coollabsio/coolify#5386

Co-authored-by: Gauthier POGAM--LE MONTAGNER <[email protected]>

Author: GauthierPLM

docs/public/images/services/signoz.svg

@@ -0,0 +1,95 @@
+---
+title: SigNoz
+description: "An observability platform native to OpenTelemetry with logs, traces and metrics."
+---
+
+# SigNoz
+
+<ZoomableImage src="/docs/images/services/signoz.svg" alt="SigNoz logo" />
+
+## What is SigNoz
+
+SigNoz is an open source observability platform native to OpenTelemetry with logs, traces and metrics.
+
+## Configuring SigNoz
+
+The following steps will guide you through the configuration of SigNoz once you have created the service in Coolify.
+
+### URLs configuration
+
+SigNoz being a whole observability platform, multiple ports need to be exposed for it to work.
+The first one is the URL of the UI. You can find it in the "Service URL" field of the Signoz service, for example: `https://signoz.example.com:8080`
+
+Then, you need to expose the Otel Collector, a service which is responsible for receiving traces, metrics and logs from your applications and services.
+It supports many different formats such as GRPC, HTTP formats, Prometheus metrics, and [many logs formats](https://signoz.io/docs/userguide/logs/) (FluentBit/FluentD, syslogs, logs from cloud services, ...).
+
+A different port is exposed for each receiver and we need to expose the relevant port for each receiver.
+You have two strategies to do so:
+- Configuring a different URL for each receiver.
+- Directly exposing the ports to the host and the outside world.
+
+Which option you prefer depends on your security needs and how you structure your domains.
+
+#### One subdomain per receiver
+
+This solution only requires you to map your subdomain to the Otel Collector service. We will cover the two default receivers, the HTTP and GRPC receivers.
+
+1. Make sure your subdomains have been registered and point to your server, such as `https://signoz-grpc.example.com` and `https://signoz-http.example.com`.
+2. Open the "Otel Collector" service settings.
+3. Add your domains with the format `https://<subdomain>.example.com:<port in container>`, separated by commas. For example: `https://signoz-grpc.example.com:4317,https://signoz-http.example.com:4318`
+
+If you want to expose additional ports / receivers, simply add a new address to the list.
+
+#### Exposing the ports on the host
+
+If you prefer to use a single domain for all receivers, you can edit the Docker Compose to directly expose the ports on the otel-collector container:
+
+```yaml
+services:
+  # ...
+otel-collector:
+  image: signoz/signoz-otel-collector:latest
+  container_name: signoz-otel-collector
+  # ...
+  ports:
+  - 4317:4317 # GRPC Collector
+  - 4318:4318 # HTTP Collector
+ 
+  # ...
+```
+
+You can now append the port to your service URL to send data to receiver: `https://signoz.example.com:4318`
+
+### Enabling SMTP emailing
+
+SigNoz uses emailing for two things: inviting users and to [send alerts](https://signoz.io/docs/alerts/).
+
+#### SigNoz emails
+
+To enable SMTP emailing (including inviting new team members), you need to set the following variables from the Environment Variables tab of your Coolify service:
+
+- `SIGNOZ_EMAILING_ENABLED` enables emailing capabilities in SigNoz.
+- `SIGNOZ_EMAILING_SMTP_ADDRESS` is the address of the SMTP server to use, in the format `host:port`.
+- `SIGNOZ_EMAILING_SMTP_FROM` is the email address to use in the From field.
+- `SIGNOZ_EMAILING_SMTP_AUTH_USERNAME` and `SIGNOZ_EMAILING_SMTP_AUTH_PASSWORD` are used to authenticate with the SMTP server.
+
+More environment variables are [available to use](https://signoz.io/docs/manage/administrator-guide/configuration/smtp-email-invitations/) to authenticate via Identity / Secret or use TLS instead of SmartTLS. Read [Passing environment variables not included in the template](passing-environment-variables-not-included-in-the-template) to learn how to add them.
+
+#### Alert Manager emails
+
+Email alerts can only be sent if an SMTP server is configured specifically for the alert manager. The global SMTP configuration and the Alert Manager configuration use different environment variables.
+
+**Note**: SigNoz has a current known issue preventing email alerting configuration from being saved. You can track the progress of this [issue in their bug tracker](https://github.com/SigNoz/signoz/issues/8478).
+
+To enable email alerts, you need to set the following variables from the Environment Variables tab of your Coolify service:
+
+- `SIGNOZ_ALERTMANAGER_SIGNOZ_GLOBAL_SMTP__SMARTHOST` is the address of the SMTP server to use, in the format `host:port`.
+- `SIGNOZ_ALERTMANAGER_SIGNOZ_GLOBAL_SMTP__FROM` is the email address to use in the From field.
+- `SIGNOZ_ALERTMANAGER_SIGNOZ_GLOBAL_SMTP__AUTH__USERNAME` and `SIGNOZ_ALERTMANAGER_SIGNOZ_GLOBAL_SMTP__AUTH__PASSWORD` are used to authenticate with the SMTP server.
+
+More environment variables are [available to use](https://signoz.io/docs/manage/administrator-guide/configuration/alertmanager/) to authenticate via Identity / Secret or use TLS instead of SmartTLS. Read [Passing environment variables not included in the template](passing-environment-variables-not-included-in-the-template) to learn how to add them.
+
+## Links
+
+- [Official Documentation](https://signoz.io/docs/introduction/)
+- [OpenTelemetry Documentation](https://opentelemetry.io/)