Merged in r_minus_1 (pull request #464)

Fix R-1

Approved-by: Steven Peters <[email protected]>

Author: chapulina

install_unstable/tutorial.md

@@ -76,7 +76,7 @@ Nightly use the following versioning scheme: `{current_released_version}+hg{date
  * `current_released_version:` will be the latest version released available in
    the changelog file of the corresponding -release repo. If the nightly is
    used for an upcoming release (for example, gazebo9) then R-1.99.99-1
-   (gazebo9_7.99.99-1) form will be used until prereleases or final release.
+   (gazebo9_8.99.99-1) form will be used until prereleases or final release.
 
  * `date`: timestamp YYYY-MM-DD