docs: fix indentation (#802)

Co-authored-by: 黄宝成 <[email protected]>

Author: little-huang

unstructured/partition/html.py

@@ -37,7 +37,7 @@ def partition_html(
 
     Parameters
     ----------
-     filename
+    filename
         A string defining the target filename path.
     file
         A file-like object using "r" mode --> open(filename, "r").