Fix typo in vocabulary.md
# Vocabulary
-For text inputs, vocabulary files should be provided in the data configuration. A vocabulary file is a simple text file with **one token per line**. It shoud starts with these 3 special tokens:
+For text inputs, vocabulary files should be provided in the data configuration. A vocabulary file is a simple text file with **one token per line**. It should start with these 3 special tokens:
```text
<blank>
