Fix typo in documentation (#743)

* Doc - Fix typo (And instance of -> An instance of)

* Add missing text_signature for WordLevel.from_file

Co-authored-by: Anthony Moi <m.anthony.moi@gmail.com>

bindings/python/py_src/tokenizers/models/__init__.pyi

@@ -294,6 +294,28 @@ class WordLevel(Model):
 
     def __init__(self, vocab, unk_token):
         pass
+    @staticmethod
+    def from_file(vocab, unk_token):
+        """
+        Instantiate a WordLevel model from the given file
+
+        This method is roughly equivalent to doing::
+
+            vocab = WordLevel.read_file(vocab_filename)
+            wordlevel = WordLevel(vocab)
+
+        If you don't need to keep the :obj:`vocab` values lying around, this method is
+        more optimized than manually calling :meth:`~tokenizers.models.WordLevel.read_file` to
+        initialize a :class:`~tokenizers.models.WordLevel`
+
+        Args:
+            vocab (:obj:`str`):
+                The path to a :obj:`vocab.json` file
+
+        Returns:
+            :class:`~tokenizers.models.WordLevel`: An instance of WordLevel loaded from file
+        """
+        pass
     def id_to_token(self, id):
         """
         Get the token associated to an ID
@@ -403,7 +425,7 @@ class WordPiece(Model):
                 The path to a :obj:`vocab.txt` file
 
         Returns:
-            :class:`~tokenizers.models.WordPiece`: And instance of WordPiece loaded from file
+            :class:`~tokenizers.models.WordPiece`: An instance of WordPiece loaded from file
         """
         pass
     def id_to_token(self, id):

bindings/python/src/models.rs

@@ -636,7 +636,7 @@ impl PyWordPiece {
     ///         The path to a :obj:`vocab.txt` file
     ///
     /// Returns:
-    ///     :class:`~tokenizers.models.WordPiece`: And instance of WordPiece loaded from file
+    ///     :class:`~tokenizers.models.WordPiece`: An instance of WordPiece loaded from file
     #[classmethod]
     #[args(kwargs = "**")]
     #[text_signature = "(vocab, **kwargs)"]
@@ -748,9 +748,10 @@ impl PyWordLevel {
     ///         The path to a :obj:`vocab.json` file
     ///
     /// Returns:
-    ///     :class:`~tokenizers.models.WordLevel`: And instance of WordLevel loaded from file
+    ///     :class:`~tokenizers.models.WordLevel`: An instance of WordLevel loaded from file
     #[classmethod]
     #[args(unk_token = "None")]
+    #[text_signature = "(vocab, unk_token)"]
     fn from_file(
         _cls: &PyType,
         py: Python,