CONTRIB: move prometheus-exporter to addons/promex
Let's start to better organize the addons by moving promex there (and
with an easier directory name). The makefile and maintainers files were
updated, as well as the CI's build matrix.
diff --git a/MAINTAINERS b/MAINTAINERS
index 2497a36..7f4881d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -119,7 +119,7 @@
Prometheus Exporter
Maintainer: Christopher Faulet <cfaulet@haproxy.com>
Maintainer: William Dauchy <wdauchy@gmail.com>
-Files: contrib/prometheus-exporter
+Files: addons/promex
Note: William is the referent regarding Prometheus. He should be consulted for
all additions and modifications of features. Christopher is the referent
for the code itself. He should be consulted for questions regarding the