doc: fix typo in HACKING

s/installion/installation
Signed-off-by: NChen Hanxiao <chenhanxiao@cn.fujitsu.com>

HACKING

@@ -45,7 +45,7 @@ post your patches:
                  --to=libvir-list@redhat.com master
 
 (Note that the "git send-email" subcommand may not be in the main git package
-and using it may require installion of a separate package, for example the
+and using it may require installation of a separate package, for example the
 "git-email" package in Fedora.) For a single patch you can omit
 "--cover-letter", but a series of two or more patches needs a cover letter. If
 you get tired of typing "--to=libvir-list@redhat.com" designation you can set

docs/hacking.html.in

@@ -45,7 +45,7 @@
                  --to=libvir-list@redhat.com master
 </pre>
         <p>(Note that the "git send-email" subcommand may not be in
-        the main git package and using it may require installion of a
+        the main git package and using it may require installation of a
         separate package, for example the "git-email" package in
         Fedora.)  For a single patch you can omit
         <code>--cover-letter</code>, but a series of two or more