notes on --without-guile

Author: stevengj

doc/docs/Installation.md

@@ -85,6 +85,8 @@ Guile is an extension/scripting language implementation based on Scheme, and we
 
 - **Important:** Most Linux distributions come with Guile already installed. You can check by seeing whether you can run `guile --version` from the command line. In that case, do **not** install your own version of Guile from source — having two versions of Guile on the same system will cause problems. However, by default most distributions install only the Guile libraries and not the programming headers — to compile libctl, you should install the **guile-devel** or **guile-dev** package.
 
+It is possible to compile libcti *without* having Guile on your system by passing `--without-guile` to the `configure` script.   (Guile is not necessary to install the Python interface to Meep and MPB.)   However, to do this, you must be building from an official `.tar.gz` package on the [releases page](https://github.com/NanoComp/libctl/releases); building directly from the libctl git repo requires Guile in order to generate certain source files.
+
 ### Building From Source
 
 Here we provide instructions for building libctl from source on Ubuntu 16.04. Gzipped tarballs of stable versions are available on the [releases page](https://github.com/NanoComp/libctl/releases).
@@ -131,4 +133,4 @@ make
 
 in the `libctl` directory. And subsequently, if you are editing the sources you should include `--enable-maintainer-mode` whenever you reconfigure. To do this, however, you will need a number of additional packages beyond those listed above:
 
--   GNU [autoconf](https://www.gnu.org/software/autoconf/autoconf.html), [automake](https://www.gnu.org/software/automake/), and [libtool](https://www.gnu.org/software/libtool/libtool.html) — these are used to create the Makefiles and configure scripts, and to build shared libraries.
+-   GNU [autoconf](https://www.gnu.org/software/autoconf/autoconf.html), [automake](https://www.gnu.org/software/automake/), and [libtool](https://www.gnu.org/software/libtool/libtool.html) — these are used to create the Makefiles and configure scripts, and to build shared libraries.