Fixed English tenses as reported by tldr-lint

pages/common/rmdir.md

@@ -2,10 +2,10 @@
 
 > Removes a directory.
 
-- Removes directory, provided it is empty. Use `rm` to remove not empty directories:
+- Remove directory, provided it is empty. Use `rm` to remove not empty directories:
 
 `rmdir {{directory}}`
 
-- Removes directories recursively (useful for nested dirs):
+- Remove directories recursively (useful for nested dirs):
 
 `rmdir -p {{path}}`