Add slow consumer docs

[mtmk]

No description provided.

[Copilot]

Pull request overview

This PR adds comprehensive documentation for handling slow consumers in NATS.Net, explaining how to detect and respond to situations where subscribers cannot keep up with the message rate. The documentation covers detection mechanisms, channel capacity tuning, and backpressure options.

Changes:

• Added new "Slow Consumers" documentation page with examples for detecting dropped messages, slow consumer episodes, tuning channel capacity, and suppressing warnings
• Updated the advanced section table of contents and intro to include the new slow consumers documentation
• Added comprehensive code examples demonstrating slow consumer handling APIs

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
tools/site_src/documentation/toc.yml	Adds "Slow Consumers" entry to the advanced topics navigation
tools/site_src/documentation/advanced/slow-consumers.md	New documentation page covering slow consumer detection, channel tuning, and warning suppression
tools/site_src/documentation/advanced/intro.md	Adds reference to the new slow consumers documentation in the "What's Next" section
tests/NATS.Net.DocsExamples/Advanced/SlowConsumerPage.cs	Provides working code examples for all slow consumer scenarios documented in the markdown file

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[Copilot]

The documentation states that BoundedChannelFullMode.DropNewest is the "default for NatsConnection" and BoundedChannelFullMode.Wait is the "default for NatsClient". While technically accurate, this could be misleading because NatsClient is a higher-level wrapper that modifies the NatsOpts.SubPendingChannelFullMode from its base default.

Consider clarifying that BoundedChannelFullMode.DropNewest is the default for the underlying NatsOpts, which NatsConnection uses directly, while NatsClient explicitly overrides this to use BoundedChannelFullMode.Wait. This would make it clearer that the difference is due to NatsClient being an opinionated wrapper rather than two separate default configurations.

Suggested change

	The `SubPendingChannelFullMode` option controls what happens when the channel is full:
	- `BoundedChannelFullMode.DropNewest` (default for `NatsConnection`) - newest messages are dropped
	- `BoundedChannelFullMode.Wait` (default for `NatsClient`) - backpressure is applied, but the server may disconnect you as a slow consumer
	The `SubPendingChannelFullMode` option controls what happens when the channel is full.
	The base default is defined on `NatsOpts` (used directly by `NatsConnection`), while `NatsClient` is a higher-level, opinionated wrapper that overrides this default:
	- `BoundedChannelFullMode.DropNewest` (default on `NatsOpts` / `NatsConnection`) - newest messages are dropped
	- `BoundedChannelFullMode.Wait` (default when using `NatsClient`, which overrides `SubPendingChannelFullMode`) - backpressure is applied, but the server may disconnect you as a slow consumer

[scottf]

LGTM