Added chart trendline example

Examples/Charts/NumberOfVisitors.ps1

@@ -0,0 +1,27 @@
+$xlfile = "$env:TEMP\visitors.xlsx"
+Remove-Item $xlfile -ErrorAction SilentlyContinue
+
+$data = ConvertFrom-Csv @"
+Week, TotalVisitors
+1,11916
+2,11665
+3,13901
+4,15444
+5,21592
+6,15057
+7,26187
+8,20662
+9,28935
+10,32443
+"@
+
+$cd = New-ExcelChartDefinition `
+    -XRange Week `
+    -YRange TotalVisitors `
+    -Title "No. Of Visitors" `
+    -ChartType ColumnClustered `
+    -NoLegend `
+    -ChartTrendLine Linear
+
+$data | Export-Excel $xlfile -Show -AutoNameRange -AutoSize -TableName Visitors -ExcelChartDefinition $cd
+