Docs: fix HAProxy name and exporter's link

doc/user/project/integrations/prometheus_library/haproxy.md

-# Monitoring HA Proxy
+# Monitoring HAProxy
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/12621) in GitLab 9.4
 
-GitLab has support for automatically detecting and monitoring HA Proxy. This is provided by leveraging the [HA Proxy Exporter](https://github.com/hnlq715/nginx-vts-exporter), which translates HA Proxy statistics into a Prometheus readable form.
+GitLab has support for automatically detecting and monitoring HAProxy. This is provided by leveraging the [HAProxy Exporter](https://github.com/prometheus/haproxy_exporter), which translates HAProxy statistics into a Prometheus readable form.
 
 ## Metrics supported
 
@@ -10,9 +10,9 @@ GitLab has support for automatically detecting and monitoring HA Proxy. This is
 | Throughput (req/sec) | sum(rate(haproxy_frontend_http_requests_total{%{environment_filter}}[2m])) |
 | HTTP Error Rate (%) | sum(rate(haproxy_frontend_http_requests_total{code="5xx",%{environment_filter}}[2m])) / sum(rate(haproxy_frontend_http_requests_total{%{environment_filter}}[2m])) |
 
-## Configuring Prometheus to monitor for HA Proxy metrics
+## Configuring Prometheus to monitor for HAProxy metrics
 
-To get started with NGINX monitoring, you should install and configure the [HA Proxy exporter](https://github.com/prometheus/haproxy_exporter) which parses these statistics and translates them into a Prometheus monitoring endpoint.
+To get started with NGINX monitoring, you should install and configure the [HAProxy exporter](https://github.com/prometheus/haproxy_exporter) which parses these statistics and translates them into a Prometheus monitoring endpoint.
 
 ## Specifying the Environment label
 

doc/user/project/integrations/prometheus_library/metrics.md

@@ -4,7 +4,7 @@
 GitLab offers automatic detection of select [Prometheus exporters](https://prometheus.io/docs/instrumenting/exporters/). Currently supported exporters are:
 * [Kubernetes](kubernetes.md)
 * [NGINX](nginx.md)
-* [HA Proxy](haproxy.md)
+* [HAProxy](haproxy.md)
 * [Amazon Cloud Watch](cloudwatch.md)
 
 We have tried to surface the most important metrics for each exporter, and will be continuing to add support for additional exporters in future releases. If you would like to add support for other official exporters, [contributions](#adding-to-the-library) are welcome.