Fix typos by codespell (#7600)

# Description

Found via `codespell -S target -L
crate,ser,numer,falsy,ro,te,nd,bu,ndoes,statics,ons,fo,rouge,pard`

# User-Facing Changes

None.

# Tests + Formatting

None and done.

# After Submitting

None.

crates/nu-utils/src/sample_config/default_config.nu

@@ -33,7 +33,7 @@ module completions {
     --write-fetch-head                            # Write fetched refs in FETCH_HEAD (default)
     --no-write-fetch-head                         # Do not write FETCH_HEAD
     --force(-f)                                   # Always update the local branch
-    --keep(-k)                                    # Keep dowloaded pack
+    --keep(-k)                                    # Keep downloaded pack
     --multiple                                    # Allow several arguments to be specified
     --auto-maintenance                            # Run 'git maintenance run --auto' at the end (default)
     --no-auto-maintenance                         # Don't run 'git maintenance' at the end
@@ -424,7 +424,7 @@ let-env config = {
   }
   menus: [
       # Configuration for default nushell menus
-      # Note the lack of souce parameter
+      # Note the lack of source parameter
       {
         name: completion_menu
         only_buffer_difference: false