Fix images in example docs #4812

Job	Run time
Build, test and upload wheel	1m 16s
Strategy / FedMedian	1m 5s
Framework / bare	1m 30s
Strategy / FedTrimmedAvg	1m 3s
Framework / bare-https	1m 19s
Strategy / QFedAvg	1m 11s
Framework / jax	4m 40s
Strategy / FaultTolerantFedAvg	1m 10s
Framework / pytorch	2m 35s
Strategy / FedAvgM	1m 15s
Framework / tensorflow	2m 57s
Strategy / FedAdam	1m 4s
Framework / tabnet	2m 39s
Strategy / FedAdagrad	1m 3s
Framework / opacus	2m 37s
Strategy / FedYogi	1m 7s
Framework / pytorch-lightning	2m 33s
Framework / mxnet	1m 38s
Framework / scikit-learn	2m 14s
Framework / fastai	3m 39s
Framework / pandas	1m 28s
	40m 3s

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