message: Update documentation to explain what to do if system has old cmake.
diff: @@ -17,6 +17,16 @@ Executable: `surelog`
  * If you do intent to change the grammar: `sudo apt-get install default-jdk ant`
  +* If you have a version of cmake before 3.13 on your system
  + (check with `cmake --version`), you need get a version that is more current.
  + On Debian-like systems (includes Ubuntu), that would be
  + ```
  + wget -q -O- https://apt.kitware.com/keys/kitware-archive-latest.asc | sudo apt-key add -
  + sudo add-apt-repository 'deb https://apt.kitware.com/ubuntu/ xenial main'
  + sudo apt-get remove -y cmake
  + sudo apt-get install -y cmake
  + ```
  +
  * Download the Surelog source code
  ```
  git clone https://github.com/alainmarcel/Surelog.git
  