Remove comments on cross-contract reentrancy venerability (#308)

## Type of change

<!--Delete points that do not apply-->

- Documentation

## Changes

The following changes have been made:

- Removed cautionary note on cross-contract vulnerability in inline docs
- Removed comment on cross-contract vulnerability in documentation
- Added note stating cross-contract reentrancy not possible but to still
exercise caution

## Notes

- Cross-contract reentrancy occurs when a contract like a vault issues
and manages assets for token contract. However, as Fuel uses native
assets, no contract call must be made to update balances. Therefore it
is not possible to perform a cross-contract reentrancy attack.
- A cautionary note on relying on other contracts for state has been
added as this can introduce dependency attacks.

## Related Issues

<!--Delete everything after the "#" symbol and replace it with a number.
No spaces between hash and number-->

Closes #307 

## Checklist

- [x] I have linked to any relevant issues.
- [x] I have commented my code, particularly in hard-to-understand
areas.
- [x] I have updated the documentation where relevant (API docs, the
reference, and the Sway book).
- [x] If my change requires substantial documentation changes, I have
[requested support from the DevRel
team](https://github.com/FuelLabs/devrel-requests/issues/new/choose)
- [x] I have added tests that prove my fix is effective or that my
feature works.
- [x] I have added (or requested a maintainer to add) the necessary
`Breaking*` or `New Feature` labels where relevant.
- [x] 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).
- [x] I have requested a review from the relevant team or maintainers.
- [x] I have updated the changelog to reflect the changes on this PR.

CHANGELOG.md

@@ -18,6 +18,7 @@ Description of the upcoming release here.
 
 - [#305](https://github.com/FuelLabs/sway-libs/pull/305) Updates to forc `v0.66.2`, fuel-core `v0.40.0`, and fuels-rs `v0.66.9`.
 - [#306](https://github.com/FuelLabs/sway-libs/pull/306) Updates the SRC-7 naming to Onchain Native Asset Metadata Standard.
+- [#308](https://github.com/FuelLabs/sway-libs/pull/308) Removes comments on Cross-Contract Reentrancy vulnerability.
 
 ### Fixed
 

docs/book/src/reentrancy/index.md

@@ -2,17 +2,12 @@
 
 The Reentrancy Guard Library provides an API to check for and disallow reentrancy on a contract. A reentrancy attack happens when a function is externally invoked during its execution, allowing it to be run multiple times in a single transaction.
 
-The reentrancy check is used to check if a contract ID has been called more than
-once in the current call stack.
+The reentrancy check is used to check if a contract ID has been called more than once in the current call stack.
 
 A reentrancy, or "recursive call" attack can cause some functions to behave in unexpected ways. This can be prevented by asserting a contract has not yet been called in the current transaction. An example can be found [here](https://swcregistry.io/docs/SWC-107).
 
 For implementation details on the Reentrancy Guard Library please see the [Sway Libs Docs](https://fuellabs.github.io/sway-libs/master/sway_libs/reentrancy/index.html).
 
-## Known Issues
-
-While this can protect against both single-function reentrancy and cross-function reentrancy attacks, it WILL NOT PREVENT a cross-contract reentrancy attack.
-
 ## Importing the Reentrancy Guard Library
 
 In order to use the Reentrancy Guard library, Sway Libs must be added to the `Forc.toml` file and then imported into your Sway project. To add Sway Libs as a dependency to the `Forc.toml` file in your project please see the [Getting Started](../getting_started/index.md).
@@ -45,3 +40,7 @@ To check if the current caller is a reentrant, you may call the `is_reentrant()`
 ```sway
 {{#include ../../../../examples/reentrancy/src/main.sw:is_reentrant}}
 ```
+
+## Cross Contract Reentrancy
+
+Cross-Contract Reentrancy is not possible on Fuel due to the use of Native Assets. As such, no contract calls are performed when assets are transferred. However standard security practices when relying on other contracts for state should still be applied, especially when making external calls.

libs/src/reentrancy.sw

@@ -15,8 +15,6 @@ use std::registers::frame_ptr;
 ///
 /// Not needed if the Checks-Effects-Interactions (CEI) pattern is followed (as prompted by the
 /// compiler).
-/// > Caution: While this can protect against both single-function reentrancy and cross-function
-/// reentrancy attacks, it WILL NOT PREVENT a cross-contract reentrancy attack.
 ///
 /// # Examples
 ///