docs: Add a note about CMake options

docs/installing-solidity.rst

@@ -230,6 +230,7 @@ Or, on Windows:
 Command-Line Build
 ------------------
 
+Solidity project uses CMake to configure the build.
 Building Solidity is quite similar on Linux, macOS and other Unices:
 
 .. code:: bash
@@ -264,6 +265,11 @@ Alternatively, you can build for Windows on the command-line, like so:
 
     cmake --build . --config RelWithDebInfo
 
+CMake options
+=============
+
+If you are interested what CMake options are available run ``cmake .. -LH``.
+
 The version string in detail
 ============================