Correction: `barStyle = BarStyle(barWidth=25)` in `README.md`

[shubham0204]

Description

barWidth is a parameter in BarStyle and not a direct parameter of BarChartData. The sample app uses the same API, but the change was not reflected in README.md for Bar Chart, The change from,

val barChartData = BarChartData(
  chartData = barChartData,
  xAxisData = xAxisData,
  yAxisData = yAxisData,
  paddingBetweenBars = 20.dp,
  barWidth = 25.dp
)

to

val barChartData = BarChartData(
  chartData = barChartData,
  xAxisData = xAxisData,
  yAxisData = yAxisData,
  paddingBetweenBars = 20.dp,
  barStyle = BarStyle( barWidth=25.dp )
)

is made by this PR.