chore: added installation package

knowledge base/linux/acl.md

@@ -8,6 +8,10 @@
 ## TL;DR
 
 ```sh
+# Install the tool.
+apt install 'acl'
+dnf install 'acl'
+
 # Show acls of files.
 getfacl 'test/declarations.h'
 

knowledge base/linux/getfattr.md

@@ -9,6 +9,10 @@
 ## TL;DR
 
 ```sh
+# Install the tool.
+apt install 'attr'
+dnf install 'attr'
+
 # Get values for specific extended attributes.
 getfattr -n 'name' 'path/to/file.1' … 'path/to/file.N'
 ```

knowledge base/linux/setfattr.md

@@ -9,6 +9,10 @@
 ## TL;DR
 
 ```sh
+# Install the tool.
+apt install 'attr'
+dnf install 'attr'
+
 # Add extended attributes.
 setfattr -n 'name' -v 'value' 'path/to/file.1' … 'path/to/file.N'