Add value labels of your data to hvplot by using parameter instead of hv.Labels()

If you want to add value labels to your data you have to overlay holoviews hv.Label() on your plot:
``` python
# import libraries
import numpy as np
import pandas as pd

import holoviews as hv
import hvplot.pandas

# create some sample data
df = pd.DataFrame({
'col1': ['bar1', 'bar2', 'bar3'],
'col2': np.random.rand(3)
})

# create your plot
plot = df.hvplot(kind='bar', x='col1', y='col2', ylim=(0, 1.2))

# create your labels separately
# kdims specifies the x and y position of your value label
# vdims specifies the column to use for the value text of your label
labels = hv.Labels(data=df, kdims=['col1', 'col2'], vdims='col2')

# use the * symbol to overlay your labels on your plot
plot * labels
```

It would be nice if you could just use something like parameter

> value_labels=True

to do this automagically right away with hvplot:
``` python
plot = df.hvplot(kind='bar', x='col1', y='col2', ylim=(0, 1.2), value_labels=True)
```

See also: [https://stackoverflow.com/questions/58900736/adding-value-labels-to-hvplot-bar](https://stackoverflow.com/questions/58900736/adding-value-labels-to-hvplot-bar)

If possible the default offset should also be a bit smart: