regroup user and group related command in User and grp management

source/Installation/linux_admin.rst

@@ -136,9 +136,11 @@ with the command.
 
     sudo visudo
 
+User and Group management
+=========================
 
 Create a new user
-=================
+-----------------
 
 .. code-block:: shell
 
@@ -147,7 +149,7 @@ Create a new user
 Only root can perform this command.
 
 Delete a user
-=============
+-------------
 
 .. code-block:: shell
 
@@ -187,8 +189,8 @@ To do this use the `-r` option
         sudo userdel -rf username
 
 
-create new group
-================
+Create new group
+----------------
 
 .. code-block:: shell
 
@@ -199,14 +201,14 @@ Only root can perform this command.
 To take into account new user and group you need to logout and login again.
 
 Delete a Group
-==============
+--------------
 
 .. code-block:: shell
 
     sudo groupdel groupname
 
 Add an Existing User to a Group
-===============================
+-------------------------------
 
 .. code-block:: shell
 
@@ -231,7 +233,7 @@ It warns you only if the user or group doesn’t exist.
 Add username to group1 and group2 in one command
 
 Remove a User From a Group
-==========================
+--------------------------
 
 .. code-block:: shell
 
@@ -239,15 +241,15 @@ Remove a User From a Group
 
 
 Check you identity
-==================
+------------------
 
 whoami
-------
+""""""
 
 To know your login
 
 id
---
+""
 
 to know your
 
@@ -264,11 +266,11 @@ to know your
 
 
 Change password
-===============
+---------------
 
 
 To change your password
------------------------
+"""""""""""""""""""""""
 
 The command to use is `passwd`
 
@@ -283,7 +285,7 @@ The command to use is `passwd`
 
 
 To change the password of another user
---------------------------------------
+""""""""""""""""""""""""""""""""""""""
 
 Only root/sudoer can change the password for another user.