Fixed URL in dependencies.md

[Hopium21]

The old link to the Bazel explanation (https://github.com/OffchainLabs/documentation/issues/138) was broken.
It has been updated to the correct working path:
OffchainLabs/prysm-documentation#138.

[prestonvanloon]

Thanks for this. Please add a changelog fragment. You can do something like this

### Ignored
- Fixed URL in dependencies.md

[Hopium21]

Thanks for this. Please add a changelog fragment. You can do something like this

### Ignored
- Fixed URL in dependencies.md

Done

[Inspector-Butters]

@Hopium21 adding a changelog fragment means adding a .md file in prysm/changelog/ explaining what was changed. create a file there with the name hopium21_fix-url-in-dependencies.md with the content:

### Ignored
- Fixed URL in dependencies.md

[prestonvanloon]

Please add a changelog fragment. See https://github.com/OffchainLabs/prysm/blob/develop/CONTRIBUTING.md#maintaining-changelogmd

[Hopium21]

#15182
created

[Inspector-Butters]

It should be in this PR, not a separate PR