[install-guide] Fix typo. BZ#1177951.

[rkratky]

commit db9a7fee73ff927436acaf298e91787f5ad29d78
Author: Robert Krátký <rkratky at redhat.com>
Date:   Thu Jan 1 19:24:47 2015 +0100

    Fix typo. BZ#1177951.

 en-US/Preparing_for_Installation.xml |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/en-US/Preparing_for_Installation.xml b/en-US/Preparing_for_Installation.xml
index b3430e9..21520e0 100644
--- a/en-US/Preparing_for_Installation.xml
+++ b/en-US/Preparing_for_Installation.xml
@@ -55,7 +55,7 @@
     <section id="sect-verifying-images">
       <title>Verifying the Downloaded Image</title>
       <para>
-        Because transmission errors or other problems may corrupt the Fedora image you have downloaded, it is imporant to verify the file's integrity.  After the images are created, an operation is performed on the file that produces a value called a <literal>checksum</literal> using a complex mathematical algorithm.  The operation is sufficiently complex that <emphasis>any change</emphasis> to the original file will produce a different checksum. 
+        Because transmission errors or other problems may corrupt the Fedora image you have downloaded, it is important to verify the file's integrity.  After the images are created, an operation is performed on the file that produces a value called a <literal>checksum</literal> using a complex mathematical algorithm.  The operation is sufficiently complex that <emphasis>any change</emphasis> to the original file will produce a different checksum. 
       </para>
       <para>
         By calculating the image's <literal>checksum</literal> on your own computer and comparing it to the original <literal>checksum</literal>, you can verify the image has not been tampered with or corrupted. The original checksum values are provided at <ulink url="https://fedoraproject.org/verify" />, and are <command>gpg</command> signed to demonstrate their integrity.