Update modrinth_mac.md

Author: Axuras

docs/launcher/modrinth_mac.md

@@ -7,3 +7,9 @@ This guide will explain the install process for Modrinth, as well as how we can
 ## How to Install (Mac)
 
 * Despite looking long, this is a very simple process and should only take a few minutes! This guide will also assume you are migrating from SkyClient, but steps will be largely the same, except for the migrating data section.
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+### Step 1 - Installing Modrinth
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+[Download Modrinth App](https://modrinth.com/app). It should automatically recommend the correct version to download (a `.dmg`). Once it is finished downloading, run it. It may warn you that it is an executable file and could be malicious. If so, follow to the next step.
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+