StorageBuckets: Fix META file

This change updates META.yml file to follow instructions
in [1]. Updates spec link now that the draft has been created,
and updates usernames to be github usernames + adds Evan.

[1] https://web-platform-tests.org/test-suite-design.html#test-layout

Bug: None
Change-Id: Ieb48a2d37a637dd23730b6ac179a5324a0812dfb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4942642
Reviewed-by: Christine Smith <[email protected]>
Commit-Queue: Ayu Ishii <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1210433}

storage/buckets/META.yml

@@ -1,5 +1,5 @@
-spec: https://github.com/WICG/storage-buckets
+spec: https://wicg.github.io/storage-buckets/
 suggested_reviewers:
-  - ayui
-  - jsbell
-  - pwnall
+  - ayuishii
+  - evanstade
+  - inexorabletash