fix typo

Author: pmiossec

book/09-git-and-other-scms/sections/import-tfs.asc

@@ -2,7 +2,7 @@
 ==== TFS
 
 (((TFS)))(((Importing, from TFS)))
-If your team is convering their source control from TFVC to Git, you'll want the highest-fidelity conversion you can get.
+If your team is converting their source control from TFVC to Git, you'll want the highest-fidelity conversion you can get.
 This means that, while we covered both git-tfs and git-tf for the interop section, we'll only be covering git-tfs for this part, because git-tfs supports branches, and this is prohibitively difficult using git-tf.
 
 [NOTE]