Typo

Co-authored-by: surfdude29 <[email protected]>

Author: estrattonbailey

blog/2025-02-14-typescript-sdk-release.md

@@ -241,7 +241,7 @@ export function isMain(value: unknown): values is Main {
 
 That implementation of the discriminator is invalid.
 
-- Fist because a `$type` is not allowed to end with `#main` (as per atproto specification).
+- First, because a `$type` is not allowed to end with `#main` (as per atproto specification).
 - Second because the `isMain` function does not actually check the structure of the object, only its `$type` property.
 
 This invalid behavior could yield runtime errors that could otherwise have been avoided during development: