Converted all arguments to the long form

pages/linux/useradd.md

@@ -8,15 +8,15 @@
 
 - Create new user with a default home directory:
 
-`useradd -m {{name}}`
+`useradd --create-home {{name}}`
 
 - Create new user with specified shell:
 
-`useradd -s {{/path/to/shell}} {{name}}`
+`useradd --shell {{/path/to/shell}} {{name}}`
 
 - Create new user belonging to additional groups (mind the lack of whitespace):
 
-`useradd -G {{group1,group2}} {{name}}`
+`useradd --groups {{group1,group2}} {{name}}`
 
 - Create new system user without a home directory: