Adding dedicated subsection to docs on Bokeh Server Jinja templating (#9531)
Adding dedicated subsection to docs on Bokeh Server Jinja templating (#9531)

* Adding dedicated subsection on Bokeh Server Jinja templating.

Final subsubsection, entitled 'Custom Jinja templates and Threading'
describes what causes !9435, and its workaround.

* Adding dedicated subsection on Bokeh Server Jinja templating.

Final subsubsection, entitled 'Custom Jinja templates and Threading'
describes what causes !9435, and its workaround.

* Removing subsubsection on templating and multiple threads.

As per discussion on PR in GH, rather going to investigate further.

* Adding HTML code example for Bokeh server custom Jinja template variables.

Makes it symmetric with the previous section.

bokeh/bokeh,bokeh/bokeh,bokeh/bokeh,ericmjl/bokeh,ericmjl/bokeh,ericmjl/bokeh,bokeh/bokeh,ericmjl/bokeh,ericmjl/bokeh,bokeh/bokeh