Added to compile notes in README.

README.md

@@ -6,8 +6,7 @@
 
 ## Requirements
 
-- `xelatex` and [`la­texmk`](http://www.ctan.org/pkg/latexmk/)
-  packaged with a modern LaTeX distribution,
+- A modern LaTeX distribution,
   e.g., [TeX Live](http://www.tug.org/texlive/).
 - [Ruby 2](https://www.ruby-lang.org/)
   with [Bundler](http://bundler.io/) (optional).
@@ -66,6 +65,9 @@ $ guard
 
 which will automatically rebuild on changes.
 
+By default, this method will use
+[`la­texmk`](http://www.ctan.org/pkg/latexmk/) with `xelatex`.
+
 ### Without Ruby
 
 To build the tex source,
@@ -75,6 +77,9 @@ $ cd tex
 $ latexmk -xelatex nonlocal_spin_valve.tex
 ````
 
+You can substitute `-xelatex` with `-pdf` to use `pdfLaTeX`.
+Alternatively, compile `nonlocal_spin_valve.tex` using your preferred method.
+
 ## License
 
 <a rel="license" href="http://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" property="dct:title">Nonlocal Spin Valve in TikZ</span> by <a xmlns:cc="http://creativecommons.org/ns#" href="https://github.com/razor-x/tikz-nonlocal_spin_valve" property="cc:attributionName" rel="cc:attributionURL">Evan Sosenko</a> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.