links to testnet installers redirect to 404 Page not Found

[web3jenks]

Summary of Bug

A clear and concise description of what the 🐞 is.
Following two links are wrong. Fixing would improve developer experience greatly as the curl download from digital ocean cdn is also not working.

docs/docs/overview/validate/joining-testnet.md

Line 20 in 0dbb684

Make sure you have [installed the Osmosis Binary (CLI)](../osmosis-core/osmosisd) prior to following the below instructions.

docs/docs/overview/validate/joining-testnet.md

Line 22 in 0dbb684

You may also [use the Osmosis installer](../osmosis-core/osmosisd) if you want everything to be done automatically.

Steps to Reproduce

Steps to reproduce the behavior:

1. click on them.

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