docs(next-config): remove mention of appIsrStatus is on canary #42532

Job	Run time
Determine changes	7s
validate-docs-links	11s
build-native / build	25s
optimize-ci / Graphite CI Optimizer	4s
build-next / build	27s
test unit	0s
test cargo unit	0s
test cargo benches	0s
ast-grep lint	14s
Run devlow benchmarks	0s
rustdoc check	0s
rust check	0s
test dev	0s
test firefox and safari	0s
test integration	0s
Test new tests for flakes (dev)	0s
Test new tests for flakes (prod)	0s
test next-swc wasi	0s
test next-swc wasm	0s
test prod	0s
test turbopack dev	0s
test turbopack development integration	0s
test turbopack production	0s
test turbopack production integration	0s
test ppr dev	0s
test ppr integration	0s
test ppr prod	0s
types and precompiled / build	55s
lint / build	1m 36s
Test new tests when deployed	0s
report test results to datadog	0s
thank you, next	1s
	4m 0s

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