Updated Barchart API (markdown)

Barchart-API.md

@@ -80,6 +80,41 @@ Refer to the the [barchartdemo](https://github.com/mum4k/termdash/blob/master/wi
 
 Both the **barchart.New** function and the **BarChart.Values** method accept options that change how the barchart behaves and looks. This section documents the individual options and their behavior.
 
+### [barchart.BarColors](https://godoc.org/github.com/mum4k/termdash/widgets/barchart#BarColors)
+
+The **barchart.BarColors** option is used to set colors of the individual bars.
+
+The following option would configure the first bar to be green and the second to be yellow. This is a partial code snippet, refer to the **barchart.New** section above for the complete code.
+
+```go
+    // snip.
+    bc.Values(values, max,
+      barchart.BarColors([]cell.Color{
+          cell.ColorGreen,
+	  cell.ColorYellow,
+      }),
+    )
+    // snip.
+```
+
+Refer to the the [barchartdemo](https://github.com/mum4k/termdash/blob/master/widgets/barchart/barchartdemo/barchartdemo.go) which demonstrates the usage of this option.
+
+### [barchart.BarGap](https://godoc.org/github.com/mum4k/termdash/widgets/barchart#BarGap)
+
+The **barchart.BarGap** option sets the widths of spacing between the bars to the provided number of terminal cells.
+
+The following option would configure the bar gap to two cells. This is a partial code snippet, refer to the **barchart.New** section above for the complete code.
+
+```go
+    // snip.
+    bc.Values(values, max, barchart.BarGap(2))
+    // snip.
+```
+
+Which results in the following barchart:
+
+[[/images/barchart-api/bar_gap.png|bar_gap]]
+
 ## Keyboard input
 
 The barchart widget doesn't support keyboard input.