fix(core): rename migrations key to nx-migrations

Rename migrations key to match what Nx is expecting

Author: Ben Callaghan

packages/core/package.json

@@ -21,7 +21,7 @@
   "bugs": {
     "url": "https://github.com/nx-dotnet/nx-dotnet/issues/new?assignees=&labels=bug%2C+needs-triage&template=bug_report.md&title=%5BBUG%5D+"
   },
-  "nx-migrate": {
+  "nx-migrations": {
     "migrations": "./migrations.json"
   }
-}
+}