fix: recreate docs folder

update.py

@@ -52,9 +52,9 @@ def generate_md(course: str, filelist_texts: str, readme_path: str):
 
 
 if __name__ == '__main__':
-    if not os.path.isdir('docs'):
-        os.mkdir('docs')
-
+    if os.path.exists('docs'):
+        shutil.rmtree('docs')
+    os.mkdir('docs')
     courses = list(filter(lambda x: os.path.isdir(x) and (
         x not in EXCLUDE_DIRS), os.listdir('.')))  # list courses
 
@@ -66,4 +66,4 @@ def generate_md(course: str, filelist_texts: str, readme_path: str):
         mainreadme_lines = file.readlines()
 
     with open('docs/index.md', 'w', encoding='utf-8') as file:
-        file.writelines(mainreadme_lines)
+        file.writelines(mainreadme_lines)