NetBox should always be referred to as NetBox

Fix all instances of "Netbox".

```Shell
git ls-files -z . | xargs --null -I '{}' find './{}' -type f -print0 | xargs --null sed --in-place --regexp-extended 's#Netbox#NetBox#g;'
```

Ref: https://netbox.readthedocs.io/en/stable/development/style-guide/#branding

build-next.sh

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Builds develop, develop-* and master branches of Netbox
+# Builds develop, develop-* and master branches of NetBox
 
 echo "▶️ $0 $*"