mkdir: add/refresh pages (#7992)

* Create `mkdir` copy with long options

* Refresh mkdir command pages:
- new example for setting permissions
- better descriptions
 - better placeholders

* Use imperative mood in titles

* Don't use brace expansion

* Apply suggestions from code review

Co-authored-by: Axel Navarro <navarroaxel@gmail.com>

* Better describe -p flag

* Remove linux/mkdir because:

- mkdir is available on several platforms

Co-authored-by: Axel Navarro <navarroaxel@gmail.com>

pages/common/mkdir.md

@@ -1,16 +1,16 @@
 # mkdir
 
-> Creates a directory.
+> Create directories and set their permissions.
 > More information: <https://www.gnu.org/software/coreutils/mkdir>.
 
-- Create a directory in current directory or given path:
+- Create specific directories:
 
-`mkdir {{path/to/directory}}`
+`mkdir {{path/to/directory1 path/to/directory2 ...}}`
 
-- Create multiple directories in the current directory:
+- Create specific directories and their [p]arents if needed:
 
-`mkdir {{directory_1 directory_2 ...}}`
+`mkdir -p {{path/to/directory1 path/to/directory2 ...}}`
 
-- Create directories recursively (useful for creating nested dirs):
+- Create directories with specific permissions:
 
-`mkdir -p {{path/to/directory}}`
+`mkdir -m {{rwxrw-r--}} {{path/to/directory1 path/to/directory2 ...}}`