[docs] revert titles

docs/Cluster-VictoriaMetrics.md

@@ -1,3 +1,5 @@
+# Cluster version of VictoriaMetrics
+
 VictoriaMetrics is fast, cost-effective and scalable time series database. It can be used as a long-term remote storage for Prometheus.
 
 It is recommended using [single-node version](https://github.com/VictoriaMetrics/VictoriaMetrics) instead of cluster version

docs/Home.md

@@ -1,4 +1,4 @@
-## VictoriaMetrics docs
+# VictoriaMetrics docs
 
 * [Quick start](Quick-Start)
 * [`WITH` templates playground](https://play.victoriametrics.com/promql/expand-with-exprs)

docs/Quick-Start.md

@@ -1,3 +1,5 @@
+# Quick Start
+
 1. Download the latest VictoriaMetrics release from [releases page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases),
    from [Docker hub](https://hub.docker.com/r/valyala/victoria-metrics/)
    or [build it from sources](https://github.com/VictoriaMetrics/VictoriaMetrics/wiki/Single-server-VictoriaMetrics#how-to-build-from-sources).

docs/Release-Guide.md

@@ -1,4 +1,4 @@
-## Release version and Docker images
+# Release version and Docker images
 
 1. Create release tag with `git tag v1.xx.y`.
 2. Run `make release` for creating `*.tar.gz` release archive with the corresponding `_checksums.txt` inside `bin` directory.

docs/Single-server-VictoriaMetrics.md

@@ -1,3 +1,5 @@
+# Single-node VictoriaMetrics
+
 VictoriaMetrics is fast, cost-effective and scalable time-series database. It can be used as long-term remote storage for Prometheus.
 It is available in [binary releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases),
 [docker images](https://hub.docker.com/r/victoriametrics/victoria-metrics/) and