fix model table cell text alignment (#14999)

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

docs/source/index.mdx

@@ -190,7 +190,7 @@ Flax), PyTorch, and/or TensorFlow.
 <!--This table is updated automatically from the auto modules with _make fix-copies_. Do not update manually!-->
 
 |            Model            | Tokenizer slow | Tokenizer fast | PyTorch support | TensorFlow support | Flax Support |
-|-----------------------------|----------------|----------------|-----------------|--------------------|--------------|
+|:---------------------------:|:--------------:|:--------------:|:---------------:|:------------------:|:------------:|
 |           ALBERT            |       ✅       |       ✅       |       ✅        |         ✅         |      ✅      |
 |            BART             |       ✅       |       ✅       |       ✅        |         ✅         |      ✅      |
 |            BEiT             |       ❌       |       ❌       |       ✅        |         ❌         |      ✅      |

utils/check_table.py

@@ -140,7 +140,8 @@ def get_model_table_from_auto_modules():
 
     # Build the table per se
     table = "|" + "|".join([_center_text(c, w) for c, w in zip(columns, widths)]) + "|\n"
-    table += "|" + "|".join(["-" * w for w in widths]) + "|\n"
+    # Use ":-----:" format to center-aligned table cell texts
+    table += "|" + "|".join([":" + "-" * (w - 2) + ":" for w in widths]) + "|\n"
 
     check = {True: "✅", False: "❌"}
     for name in model_names: