How can I add text annotation in Bokeh?

As of version 0.12.2, to add text annotations you would use the "label" glyph.

from bokeh.models import Label

p = figure(...)

mytext = Label(x=70, y=70, text='here your text')

p.add_layout(mytext)

show(p)

Please find a full example in the documentation: http://docs.bokeh.org/en/latest/docs/user_guide/annotations.html#userguide-annotations

This 'text' functionality falls under 'glyphs': you'll find the page here