docs: Update README with start_sync_server section

[camdecoster]

Description

Update the README to include section about keeping Chrome running. Also fix syntax issues in examples.

Changes

• Update README

Notes

• start_sync_server is undocumented at the moment
• I mentioned it in this issue report to try to unblock some users

[emilykl]

Suggested change

	import asyncio
	import kaleido
	async with kaleido.Kaleido(n=4, timeout=90) as k:
	# n is number of processes
	await k.write_fig(fig, path="./", opts={"format":"jpg"})
	async def main():
	async with kaleido.Kaleido(n=4, timeout=90) as k:
	# n is number of processes
	await k.write_fig(fig, path="./", opts={"format": "jpg"})
	import asyncio
	import kaleido
	import plotly.express as px
	async def main():
	# n is number of processes
	async with kaleido.Kaleido(n=4, timeout=90) as k:
	# fig is a plotly figure object
	fig = px.scatter(x=[1, 2, 3, 4], y=[2, 1, 4, 3])
	await k.write_fig(fig, path="./", opts={"format": "jpg"})

[emilykl]

Suggestion to include code which declares fig_objects for clarity on the exact structure of the object.

Suggested change

	# You can also use Kaleido.write_fig_from_object, where fig_objects is
	# an iterable of dicts each expanded to the write_fig arguments (fig,
	# path, opts, topojson):
	await k.write_fig_from_object(fig_objects)
	# You can also use Kaleido.write_fig_from_object, where fig_objects is
	# an iterable of dicts each expanded to the write_fig arguments (fig,
	# path, opts, topojson):
	fig_objects = [
	{
	"fig": px.scatter(x=[1, 2, 3, 4], y=[2+i, 1+i, 4+i, 3+i]),
	"path": f"fig_{i}.jpg",
	"opts": {"format": "jpg"},
	} for i in range(10)
	]
	await k.write_fig_from_object(fig_objects)

[emilykl]

Suggested change

	# - fig: A single plotly figure or an iterable.
	# - path: A directory (names auto-generated based on title)
	# or a single file.
	# - opts: A dictionary with image options:
	# `{"scale":..., "format":..., "width":..., "height":...}`
	# - cancel_on_error: If False (default), errors during rendering are collected
	# and returned as a tuple after all figures are attempted.
	# If True, the first error is raised immediately and any
	# remaining renders are cancelled.
	# - fig: (required) A single plotly figure or an iterable.
	# - path: (optional) A directory (names auto-generated based on title)
	# or a single file.
	# - opts: (optional) A dictionary with image options:
	# `{"scale":..., "format":..., "width":..., "height":...}`
	# - cancel_on_error: (optional) If False (default), errors during rendering are collected
	# and returned as a tuple after all figures are attempted.
	# If True, the first error is raised immediately and any
	# remaining renders are cancelled.

[emilykl]

Suggested change

	### Keeping Chrome warm across calls
	### Generate multiple images faster by reusing the same Chrome instance

[emilykl]

Suggested change

	Call `kaleido.start_sync_server()` once at the top of your script to keep
	a single Chrome instance warm and reuse it across all subsequent sync
	calls, including `fig.write_image()`:
	Call `kaleido.start_sync_server()` once at the top of your script to start
	a single Chrome instance and reuse it across all subsequent sync
	calls, including `fig.write_image()`:

[emilykl]

Suggested change

	in one script, the per-call Chrome startup and shutdown cost will
	in one script, the per-call Chrome startup and shutdown delay will

[emilykl]

Suggested change

	The `page_generator` argument takes a `kaleido.PageGenerator()` to customize versions.
	Normally, kaleido looks for an installed copy of plotly and uses that version. You can pass
	The `page_generator` argument takes a `kaleido.PageGenerator()` to customize which versions
	of plotly.js, MathJax, and other scripts are used when generating an image.
	If plotly is installed, kaleido defaults to the version of plotly.js contained in that package. You can pass

[emilykl]

Suggested change

	`kaleido.PageGenerator(force_cdn=True)` to force use of a CDN version of plotly (the
	default if plotly is not installed).
	`kaleido.PageGenerator(force_cdn=True)` to force use of a CDN version of plotly (which is
	the default behavior if plotly is not installed).