Merge branch 'docs/gitlab-basics-community-contribution' into 'master'

Add alerts to GitLab basics

See merge request gitlab-org/gitlab-ce!30071

doc/gitlab-basics/command-line-commands.md

@@ -29,7 +29,9 @@ git clone PASTE HTTPS OR SSH HERE
 
 A clone of the project will be created in your computer.
 
->**Note:** If you clone your project via a URL that contains special characters, make sure that characters are URL-encoded.
+NOTE: **Note:**
+If you clone your project via a URL that contains special characters, make sure
+that characters are URL-encoded.
 
 ### Go into a project directory to work in it
 
@@ -86,12 +88,18 @@ cat README.md
 
 ### Remove a file
 
+DANGER: **Danger:**
+This will permanently delete the file.
+
 ```
 rm NAME-OF-FILE
 ```
 
 ### Remove a directory and all of its contents
 
+DANGER: **Danger:**
+This will permanently delete the directory and all of its contents.
+
 ```
 rm -r NAME-OF-DIRECTORY
 ```
@@ -113,9 +121,13 @@ history
 You will be asked for an administrator’s password.
 
 ```
-sudo
+sudo COMMAND
 ```
 
+CAUTION: **Caution:**
+Be careful of the commands you run with `sudo`. Certain commands may cause
+damage to your data and system.
+
 ### Show which directory I am in
 
 ```