docs(framework:skip) Add FLWR_VERSION_REF to docs #15278

Job	Run time
Build, test and upload wheel	1m 19s
Strategy / FedMedian	1m 13s
Framework / e2e-bare	3m 41s
Strategy / FedTrimmedAvg	1m 10s
Template / numpy	1m 8s
Framework / e2e-bare-https	1m 7s
Strategy / QFedAvg	2m 56s
Template / pytorch	2m 35s
Framework / e2e-bare-auth	58s
Strategy / FaultTolerantFedAvg	1m 12s
Framework / e2e-jax	1m 25s
Template / tensorflow	2m 8s
Strategy / FedAvgM	1m 10s
Framework / e2e-pytorch	2m 24s
Template / jax	1m 13s
Strategy / FedAdam	1m 13s
Framework / e2e-tensorflow	3m 46s
Strategy / FedAdagrad	1m 12s
Template / sklearn	1m 53s
Framework / e2e-opacus	2m 25s
Strategy / FedYogi	1m 47s
Framework / e2e-pytorch-lightning	1m 42s
Framework / e2e-scikit-learn	1m 38s
Framework / e2e-fastai	2m 36s
Framework / e2e-pandas	1m 5s
	44m 56s

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