Improve the README section on color themes

README.md

@@ -521,12 +521,15 @@ line:
 Or you can use another theme altogether by adding something in `personal/preload` like:
 
 ```lisp
+(prelude-require-package 'solarized)
 (setq prelude-theme 'solarized-dark)
 ```
 
-**P.S.** Solarized is not available by default - you'll have to
-  install it from MELPA first (`M-x package-install RET
-  solarized-theme`).
+**Note** [Solarized](https://github.com/bbatsov/zenburn-emacs) is not
+available by default - you'll have to install it from MELPA first,
+therefore the need for `prelude-require-package`.  Alternatively you
+can manually install the package like this - `M-x package-install RET
+solarized-theme`.
 
 Finally, if you don't want any theme at all, you can add this to your
 `personal/preload`: