http.bzl: Use syntactically correct checksums in examples
http.bzl: Use syntactically correct checksums in examples

The Starlark version of http_archive comes with some documenting examples,
that also provide the sha256 parameter, as is best practice. However, the
example value is not syntactically a sha256 sum (in fact, it has to the
length of a sha1 sum) which can be irritating. Therefore, replace it with
a proper sha256 sum (that of the empty string).

Change-Id: I6ea7b4aa0f8b3603b670400650ca64cd8082cf61
PiperOrigin-RevId: 245410913

twitter-forks/bazel,cushon/bazel,ulfjack/bazel,cushon/bazel,aehlig/bazel,safarmer/bazel,dslomov/bazel,dslomov/bazel,aehlig/bazel,safarmer/bazel,katre/bazel,davidzchen/bazel,davidzchen/bazel,cushon/bazel,perezd/bazel,dslomov/bazel-windows,werkt/bazel,ulfjack/bazel,dslomov/bazel,dslomov/bazel,perezd/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,aehlig/bazel,katre/bazel,aehlig/bazel,safarmer/bazel,bazelbuild/bazel,dslomov/bazel-windows,dslomov/bazel,twitter-forks/bazel,ulfjack/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,akira-baruah/bazel,davidzchen/bazel,perezd/bazel,davidzchen/bazel,bazelbuild/bazel,davidzchen/bazel,meteorcloudy/bazel,safarmer/bazel,perezd/bazel,dslomov/bazel-windows,katre/bazel,akira-baruah/bazel,dslomov/bazel-windows,twitter-forks/bazel,dslomov/bazel-windows,cushon/bazel,katre/bazel,perezd/bazel,werkt/bazel,twitter-forks/bazel,aehlig/bazel,werkt/bazel,aehlig/bazel,twitter-forks/bazel,meteorcloudy/bazel,ulfjack/bazel,cushon/bazel,meteorcloudy/bazel,werkt/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,werkt/bazel,dslomov/bazel,meteorcloudy/bazel,katre/bazel,aehlig/bazel,ulfjack/bazel,werkt/bazel,twitter-forks/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,ulfjack/bazel,safarmer/bazel,ButterflyNetwork/bazel,davidzchen/bazel,bazelbuild/bazel,ulfjack/bazel,safarmer/bazel,akira-baruah/bazel,cushon/bazel,perezd/bazel,dslomov/bazel,davidzchen/bazel,twitter-forks/bazel,dslomov/bazel-windows,meteorcloudy/bazel,perezd/bazel,katre/bazel,akira-baruah/bazel,akira-baruah/bazel,akira-baruah/bazel,bazelbuild/bazel