update documentation for `bokeh.models.CrosshairTool` (#6652)
update documentation for `bokeh.models.CrosshairTool` (#6652)

* Update tools.rst

* Update tools.rst

* Update tools.rst

fix trailing whitespace

* Update tools.rst

rs2/bokeh,DuCorey/bokeh,Karel-van-de-Plassche/bokeh,dennisobrien/bokeh,bokeh/bokeh,stonebig/bokeh,ericmjl/bokeh,philippjfr/bokeh,dennisobrien/bokeh,Karel-van-de-Plassche/bokeh,jakirkham/bokeh,bokeh/bokeh,bokeh/bokeh,dennisobrien/bokeh,ericmjl/bokeh,rs2/bokeh,rs2/bokeh,ericmjl/bokeh,aavanian/bokeh,timsnyder/bokeh,timsnyder/bokeh,bokeh/bokeh,dennisobrien/bokeh,DuCorey/bokeh,timsnyder/bokeh,timsnyder/bokeh,DuCorey/bokeh,jakirkham/bokeh,mindriot101/bokeh,timsnyder/bokeh,aavanian/bokeh,ericmjl/bokeh,dennisobrien/bokeh,rs2/bokeh,mindriot101/bokeh,stonebig/bokeh,jakirkham/bokeh,jakirkham/bokeh,stonebig/bokeh,aavanian/bokeh,DuCorey/bokeh,aavanian/bokeh,philippjfr/bokeh,Karel-van-de-Plassche/bokeh,aavanian/bokeh,mindriot101/bokeh,rs2/bokeh,philippjfr/bokeh,philippjfr/bokeh,bokeh/bokeh,philippjfr/bokeh,ericmjl/bokeh,stonebig/bokeh,Karel-van-de-Plassche/bokeh,Karel-van-de-Plassche/bokeh,jakirkham/bokeh,DuCorey/bokeh,mindriot101/bokeh