docs/reference-table: Add intel-cl

Because the Intel compiler behaves significantly differently on windows
than it does on Linux and MacOS I've decided it would be better to
follow the clang/clang-cl split and make id "intel-cl" on windows
(leaving "intel" alone on Linux and Mac). Since we've never supported
ICL and it hasn't worked in the past I think this is an okay change to
make.

docs/markdown/Reference-tables.md

@@ -16,7 +16,8 @@ These are return values of the `get_id` (Compiler family) and
 | flang     | Flang Fortran compiler           |                 |
 | g95       | The G95 Fortran compiler         |                 |
 | gcc       | The GNU Compiler Collection      | gcc             |
-| intel     | Intel compiler                   | msvc on windows, otherwise gcc |
+| intel     | Intel compiler (Linux and Mac)   | gcc             |
+| intel-cl  | Intel compiler (Windows)         | msvc            |
 | lcc       | Elbrus C/C++/Fortran Compiler    |                 |
 | llvm      | LLVM-based compiler (Swift, D)   |                 |
 | mono      | Xamarin C# compiler              |                 |