docs: add epilog.rst to define common things.

docs/glossary.rst

@@ -3,6 +3,24 @@ Glossary
 
 .. glossary::
 
+   `Virtual machine`_
+
+      A Virtual machine is a program that can execute an entire
+      operatin system inside an emulated hardware environment.
+
+   `Container`_
+
+      A Container is an isolated user space. Programs runs directly on
+      the hosts kernel, but with limited access to the host resources.
+
+   `Rust`_
+
+      Rust is a new, fast and memory-efficient system programming
+      language, with no runtime or garbage collector. Rust’s rich type
+      system and ownership model guarantee memory-safety and
+      thread-safety. I can eliminate many classes of bugs
+      at compile-time.
+
    `Sphinx`_
 
       Is a tool that makes it easy to create intelligent and
@@ -16,7 +34,3 @@ Glossary
 
       Is an easy-to-read, what-you-see-is-what-you-get plaintext
       markup syntax and parser system.
-
-
-.. _Sphinx: https://www.sphinx-doc.org
-.. _reStructuredText: https://www.sphinx-doc.org/en/master/usage/restructuredtext/index.html