always_include_global_tags should be documented to work only with [[inputs]]

### Relevant telegraf.conf

```toml
na
```

### Logs from Telegraf

```text
na
```

### System info

Telegraf 1.32.1

### Docker

_No response_

### Steps to reproduce

na

### Expected behavior

Agent documenation https://github.com/influxdata/telegraf/blob/master/docs/CONFIGURATION.md#agent should explain, that option `always_include_global_tags` is only working for [[inputs]] and NOT for [[outputs]]. You can set `taginclude` also for outputs and so we thought, that `always_include_global_tags` will also work here.
Unfortunately there does not exist any option like `always_include_global_tags` for [[outputs]]

### Actual behavior

na

### Additional info

_No response_

Start with docs/CONFIGURATION.md and its agent section, which the issue links directly. Clarify there that always_include_global_tags applies only to [[inputs]] and not [[outputs]], and that outputs have no equivalent option; done means the documentation removes this ambiguity.

Written by the indexing model from the issue text.