fix(typo): isthumus to isthmus.

Author: scharissis

pages/notices/upgrade-15.mdx

@@ -17,7 +17,7 @@ is_imported_content: 'false'
 
 import { Steps, Callout } from 'nextra/components'
 
-# Upgrade 15: Isthumus Hard Fork
+# Upgrade 15: Isthmus Hard Fork
 
 This page outlines breaking changes related to the Isthmus network upgrade for chain operators and node operators. The upgrade proposal is available [here](https://gov.optimism.io/t/upgrade-proposal-15-isthmus-hard-fork/9804) and the governance vote is available [here](https://gov.optimism.io/t/proposal-preview-implement-prague-features-on-the-op-stack/9703).
 

words.txt

@@ -180,7 +180,7 @@ ipcfile
 IPCPATH
 ipcpath
 IPFS
-Isthumus
+Isthmus
 JALR
 JOURNALREMOTES
 journalremotes