metrics: Add report file titles

This PR adds report file titles for kata metrics.

Signed-off-by: Gabriela Cervantes <gabriela.cervantes.tellez@intel.com>

tests/metrics/report/report_dockerfile/html.Rmd

@@ -0,0 +1,23 @@
+---
+# Copyright (c) 2018-2023 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+title: "Kata Containers metrics report"
+author: "Auto generated"
+date: "`r format(Sys.time(), '%d %B, %Y')`"
+output:
+  html_document:
+urlcolor: blue
+---
+
+```{r setup, include=FALSE}
+#Set these opts to get pdf images which fit into beamer slides better
+opts_chunk$set(dev = 'png')
+# Pick up any env set by the invoking script, such as the root dir of the
+# results data tree
+source("/inputdir/Env.R")
+```
+
+```{r child = 'metrics_report.Rmd'}
+```