Update misspell to 0.5.1 and add misspellings.csv (#30573)

Misspell 0.5.0 supports passing a csv file to extend the list of
misspellings, so I added some common ones from the codebase. There is at
least one typo in a API response so we need to decided whether to revert
that and then likely remove the dict entry.

routers/api/packages/README.md

@@ -19,7 +19,7 @@ The package registry code is divided into multiple modules to split the function
 
 ## Models
 
-Every package registry implementation uses the same underlaying models:
+Every package registry implementation uses the same underlying models:
 
 | Model | Description |
 | - | - |