Docs should specify what the default app max concurrency is

[KrylixZA]

What content needs to be created or modified?
There is no documentation about the default value the app-max-concurrency is. The documentation purely mentions the following:

Limit the concurrency of your application. A valid value is any number larger than 0

Describe the solution you'd like
The documentation should specify what the default maximum concurrency is. Even if it is unbounded, it should be documented.

Limit the concurrency of your application. A valid value is any number larger than 0. Default is unbounded and only limited by your application's ability to concurrently handle requests.

Where should the new material be placed?
Possibly under the Dapr arguments and annotations for daprd, CLI, and Kubernetes page? I think if you're going as far down into Dapr's configuration as using Dapr for rate limiting, you probably understand enough and have Googled enough to find this page. For the majority of users it's unlikely they will need to change this setting so it's probably okay to simply append to the existing documentation.

The associated pull request from dapr/dapr, dapr/components-contrib, or other Dapr code repos

Additional context
I am busy experimenting with app concurrency in an attempt to resolve issues around contention of resources. Currently we've not set any value for this but it's hard to know whether my change will make things better or worse without a baseline to compare against.