MINOR: version: mention that it's LTS now.

The version will be maintained up to around Q2 2028. Let's
also update the INSTALL file to mention this.
diff --git a/INSTALL b/INSTALL
index 622fcc0..71885e5 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,15 +1,19 @@
 Installation instructions for HAProxy
 =====================================
 
-This is a development version, so it is expected to break from time to time,
-to add and remove features without prior notification and it should not be used
-in production, unless you're an experienced user and are willing to follow
-weekly updates. If you are not used to build from sources or if you are not
-used to follow updates then it is recommended that instead you use the packages
-provided by your software vendor or Linux distribution. Most of them are taking
-this task seriously and are doing a good job at backporting important fixes.
+HAProxy 2.8 is a long-term supported version, which means that it will get
+fixes for bugs as they are discovered till around Q2 2028 and will not receive
+new features. This version is suitable for general deployment as it is expected
+to receive less frequent updates than regular stable branches which have an odd
+digit in the minor version number. New users are encouraged to use long-term
+supported versions such as the ones provided by their software vendor, Linux
+distribution, or by a trusted package maintainer. Experienced users who manage
+a fleet of load balancers are encouraged to deploy at least one node with the
+latest weekly development version to get familiar with upcoming changes and
+possibly detect unwelcome changes or bugs before the release. This is also a
+great way to get new features implemented exactly as desired.
 
-If for any reason you'd prefer to use a different version than the one packaged
+If for any reason you would prefer a different version than the one packaged
 for your system, you want to be certain to have all the fixes or to get some
 commercial support, other choices are available at http://www.haproxy.com/.