Update README.md

Author: mvallim

README.md

@@ -30,6 +30,19 @@ See also the list of [contributors](CONTRIBUTORS.txt) who participated in this p
 * `live system` - the computer environment that runs from the live OS, generated by a `build system`.  This may also be referred to as the `chroot environment`.
 * `target system` - the computer environment that runs after installation has completed from a `live system`.
 
+> [!IMPORTANT]
+> It is very important to remember that the version you are generating depends on the version being used on the host machine.
+>
+> Example:
+> If I am generating a from scratch `bionic` version, it is necessary for the host machine to have a `bionic` version or higher installed.
+>
+> | Scratch  | Host        |
+> |:--------:|:-----------:|
+> | `bionic` | `>= bionic` |
+> | `focal`  | `>= focal`  |
+> | `jammy`  | `>= jammy`  |
+> | `noble`  | `>= noble`  |
+
 ## Prerequisites (GNU/Linux Debian/Ubuntu)
 
 Install packages we need in the `build system` required by our scripts.