Update content/investigating-lang-ext-semantics/index.md

Co-authored-by: Hécate <Kleidukos@users.noreply.github.com>

Author: jappeace

content/investigating-lang-ext-semantics/index.md

@@ -169,7 +169,7 @@ The issue is discussed [here](https://gitlab.haskell.org/ghc/ghc/-/issues/23719)
 From what I understand from the [manual](https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/type_abstractions.html#type-abstractions)
 is that part of the syntax for type abstractions landed in GHC 9.2,
 however 9.8 and onwards requires you to enable this language extension.
-This appears to because certain new functionality was introduced behind an
+This appeared because certain new functionality was introduced behind an
 old language extension flag, according to [this proposal](https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0448-type-variable-scoping.rst#4type-arguments-in-constructor-patterns)
 
 This extension enables you to bind type variables in pattern matches.