docs: remove missing feature regarding configurables (FuelLabs#4317)

## Description

FuelLabs#2647 has been resolved.

## Checklist

- [ ] I have linked to any relevant issues.
- [ ] I have commented my code, particularly in hard-to-understand
areas.
- [ ] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [ ] I have added tests that prove my fix is effective or that my
feature works.
- [ ] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [ ] I have done my best to ensure that my PR adheres to [the Fuel Labs
Code Review
Standards](https://github.com/FuelLabs/rfcs/blob/master/text/code-standards/external-contributors.md).
- [ ] I have requested a review from the relevant team or maintainers.

docs/book/src/reference/known_issues_and_workarounds.md

@@ -10,8 +10,6 @@
 
 * [#1796](https://github.com/FuelLabs/sway/issues/2465): It is not yet allowed to use `StorageMap<K, V>` as a component of a complex type such as a struct or an enum.
 
-* [#2647](https://github.com/FuelLabs/sway/issues/2647): Currently, it is only possible to define configuration-time constants that have [primitive types](../basics/built_in_types.md#primitive-types) and that are initialized using literals.
-
 ## General
 
 * No compiler optimization passes have been implemented yet, therefore bytecode will be more expensive and larger than it would be in production. Note that eventually the optimizer will support zero-cost abstractions, avoiding the need for developers to go down to inline assembly to produce optimal code.