docs: contributing guide update (#3409)

* docs: Update contributing guide on how to work with unreleased forc and fuel-core functionality

* docs: Add further notes to contributing guide

• Added note on what files are created after intalling `forc` and `fuel-core`
• Added a note that resolves the issue that arises when using standard binaries
but it uses the previously downloaded binaries.

* docs: Add a note stating the contents of the downloaded repos.

* chore: rearranged notes

* chore: added not on running the e2e-script

* Apply suggestions from code review

Co-authored-by: Daniel Bate <[email protected]>

---------

Co-authored-by: Richard Gregory <[email protected]>
Co-authored-by: Anderson Arboleya <[email protected]>
Co-authored-by: Sérgio Torres <[email protected]>
Co-authored-by: Daniel Bate <[email protected]>

CONTRIBUTING.md

@@ -109,6 +109,85 @@ See also:
 
 - [Developing](#developing)
 
+# Working with Unreleased Forc and Fuel-Core Functionality
+
+When you need to work with unreleased versions of `forc` or `fuel-core`, you can specify a git branch instead of a version number in the respective `VERSION` file.
+
+## Using Unreleased Forc
+
+To use an unreleased version of `forc`:
+
+1.  **Edit the `VERSION` File**
+    Open the `internal/forc/VERSION` file and replace the version number (e.g., `0.59.0`) with the desired git branch:
+
+        ```text
+        git:some/branch-name
+        ```
+
+1.  **Install and Build**
+    To download and build `forc` from the specified branch after updating `VERSION` file, run:
+
+        ```sh
+        pnpm install
+        pnpm build
+        ```
+
+The following directory will be updated or created: `internal/forc/sway-repo`
+
+## Using Unreleased Fuel-Core
+
+Similarly, to use an unreleased version of `fuel-core`:
+
+1.  **Edit the `VERSION` file:**
+    Open the `internal/fuel-core/VERSION` file and replace the version number with the desired git branch:
+
+        ```text
+        git:some/branch-name
+        ```
+
+1.  **Install and Build**
+    To download and build `fuel-core` from the specified branch after updating `VERSION` file, run:
+
+        ```sh
+        pnpm install
+        pnpm build
+        ```
+
+> [!Note]
+> The `internal/forc/sway-repo` and `internal/fuel-core/fuel-core-repo` directory will contain a local clone of the Sway and Fuel Core repository respectively, at the specific version or git branch you have specified in the `internal/forc/VERSION` and `internal/fuel-core/VERSION` file.
+
+## Unreleased Files and Directories Created After Installation
+
+After running `pnpm install` and `pnpm build`, the following files and directories are created:
+
+- Forc Repository:
+
+  - Located at `internal/forc/sway-repo`.
+  - Contains the source code for the version of `forc` you are using.
+
+- Fuel-Core Repository:
+  - Located at `internal/fuel-core/fuel-core-repo`.
+  - Contains the source code for the version of `fuel-core` you are using.
+
+## Switching Back to Standard Binaries
+
+If you switch back to using standard binaries you might encounter issues where the SDK still uses the previously downloaded unreleased binaries.
+
+To resolve the issue and ensure the SDK uses the correct binaries:
+
+1. **Delete the downloaded repositories**
+
+   ```sh
+   rm -rf internal/forc/sway-repo
+   rm -rf internal/fuel-core/fuel-core-repo
+   ```
+
+1. **Reinstall and build**
+   ```sh
+   pnpm install
+   pnpm build
+   ```
+
 # Testing
 
 In order to run tests locally, you can run the following commands:
@@ -182,6 +261,12 @@ DEVNET_WALLET_PVT_KEY=0x...
 TESTNET_WALLET_PVT_KEY=0x...
 ```
 
+This will enable you to run the e2e test locally against the live network:
+
+```sh
+pnpm test:filter e2e-script
+```
+
 <!-- TODO: add/fix block explorer URL after testnet support- Checking Wallet Balance: https://fuellabs.github.io/block-explorer-v2/beta-5/?#/address/fuel1x33ajpj0jy5p2wcqqu45e32r75zrwfeh6hwqfv5un670rv4p0mns58enjg -->
 
 # Commit Convention