[Linux] Add Linux file system layout section

Author: shorodilov

assets/img/linux-fs-layout.png

@@ -64,3 +64,23 @@ of each input line:
 +--------+--------------+
 | ``b``  | Block device |
 +--------+--------------+
+
+Linux file system layout
+========================
+
+For convenience, the Linux file system is usually thought of in a tree
+structure.
+
+.. figure:: /../assets/img/linux-fs-layout.png
+    :align: center
+
+    RedHat system layout
+
+The tree of the file system starts at the trunk or *slash*, indicated by
+a forward slash (``/``). This directory, containing all underlying directories
+and files, is also called the *root directory* or the **root* of the file
+system.
+
+Directories that are only one level below the root directory are often preceded
+by a slash, to indicate their position and prevent confusion with other
+directories that could have the same name.