Change quotation marks to be bash pastable.

Bug: None
Change-Id: I39c221fd574b9d19fe0d9cbabf81769644823e90
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2627142Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Commit-Queue: benjamin joyce <bjoyce@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843122}

docs/testing/code_coverage.md

@@ -188,7 +188,7 @@ mode, where `N` is the number of raw profiles. With `N = 4`, the total size of
 the raw profiles are limited to a few gigabytes.
 
 ```
-$ export LLVM_PROFILE_FILE=”out/report/crypto_unittests.%4m.profraw”
+$ export LLVM_PROFILE_FILE="out/report/crypto_unittests.%4m.profraw"
 $ ./out/coverage/crypto_unittests
 $ ls out/report/
 crypto_unittests.3657994905831792357_0.profraw