Add section to documentation about updating package version

Document includes a description for pumping the release, but what
if there is a completely new upstream version?  This patch adds a
section that describes how to update the upstream url for a
package and update the package information accordingly.

Signed-off-by: Kevron Rees <kevron.m.rees@intel.com>

README.md

@@ -102,6 +102,10 @@ $ echo missing-build-req >> buildreq_add
 $ make autospec
 ```
 
+Please see https://github.com/clearlinux/autospec#common-files for 
+documention on buildreq_add and the other files autospec uses during the
+build process.
+
 ### Bump the release number for a package
 
 If you simply need to increment a package's release number and rebuild the
@@ -112,6 +116,16 @@ $ make bump
 $ make build
 ```
 
+### Update the release version for a package
+
+If you have an update release version for a package, you can change the url
+for the new release in the package/example-pkg/Makefile.  After modifying the
+new url, run `make autospec` again to fetch the new package and rebuild.
+
+```
+$ make autospec
+```
+
 ## Other topics
 
 ### Customizing the mock config