docs: Task outputs clarifications (#9185)

To avoid the impression that cache is disabled when Task `outputs` key
is ommitted.

`API reference` was more accurate for that behavior, than `Crafting your
repository`.

### Description

I'm new to Turborepo, and was reading [Crafting your
repository](https://turbo.build/repo/docs/crafting-your-repository). Two
sections lead me to conclude that when there is no `outputs` key in a
Task, then caching is disabled. I think the wording in `API reference`
is better.

We have to account for Logs output even if there are no file outputs
(which is really nice for linters).

### Testing Instructions

* Review the modified documentations.
* Take into account that I'm not a native english speaker (you probably
notice already ;) )

docs/repo-docs/crafting-your-repository/caching.mdx

@@ -121,10 +121,14 @@ For information on how to connect your CI machines to Remote Cache, visit [the C
 
 ## What gets cached?
 
+Turborepo caches two types of outputs: Task outputs and Logs.
+
 ### Task outputs
 
 Turborepo caches the file outputs of a task that are defined in [the `outputs` key](/repo/docs/reference/configuration#outputs) of `turbo.json`. When there's a cache hit, Turborepo will restore the files from the cache.
 
+The `outputs` key is optional, see [the API reference](/repo/docs/reference/configuration#outputs) for how Turborepo behaves in this case.
+
 <Callout type="warn" title="Providing file outputs">
 If you do not declare file outputs for a task, Turborepo will not cache them. This might be okay for some tasks (like linters) - but many tasks produce files that you will want to be cached.
 

docs/repo-docs/reference/configuration.mdx

@@ -339,8 +339,6 @@ An allowlist of environment variables that should be made available to this task
 
 A list of file glob patterns relative to the package's `package.json` to cache when the task is successfully completed.
 
-Omitting this key or passing an empty array tells `turbo` to cache nothing (except logs, which are always cached when caching is enabled).
-
 ```jsonc title="./turbo.json"
 {
   "tasks": {
@@ -352,6 +350,8 @@ Omitting this key or passing an empty array tells `turbo` to cache nothing (exce
 }
 ```
 
+Omitting this key or passing an empty array tells `turbo` to cache nothing (except logs, which are always cached when caching is enabled).
+
 ### `cache`
 
 Default: `true`