Fix kEnableSignedExchangeSubresourcePrefetchDescription

I submitted crrev.com/c/1619582 before fixing misspelling.

TBR=ksakamoto@chromium.org

Bug: 935267
Change-Id: I7611ccabbf05bbc6d7139efde3a1275537abf16c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1619592
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661326}
1 file changed