Remove the section for uploading protoc packages to the GitHub release page

Currently this is managed by the release script. We should also possibly remove the section for "Push artifacts to Maven Central"

protoc-artifacts/README.md

@@ -151,31 +151,6 @@ https://oss.sonatype.org/#stagingRepositories and find the repository, usually
 in the name like ``comgoogle-123``. Verify that the staging repository has all
 the binaries, close and release this repository.
 
-## Upload zip packages to github release page.
-After uploading protoc artifacts to Maven Central repository, run the
-build-zip.sh script to bulid zip packages for these protoc binaries
-and upload these zip packages to the download section of the github
-release. For example:
-
-```
-$ ./build-zip.sh protoc 3.6.0
-```
-
-The above command will create 7 zip files:
-
-```
-dist/protoc-3.6.0-win32.zip
-dist/protoc-3.6.0-osx-x86_32.zip
-dist/protoc-3.6.0-osx-x86_64.zip
-dist/protoc-3.6.0-linux-x86_32.zip
-dist/protoc-3.6.0-linux-x86_64.zip
-dist/protoc-3.6.0-linux-aarch_64.zip
-dist/protoc-3.6.0-linux-ppcle_64.zip
-dist/protoc-3.6.0-linux-s390x_64.zip
-```
-
-Before running the script, make sure the artifacts are accessible from:
-http://repo1.maven.org/maven2/com/google/protobuf/protoc/
 
 ## Tested build environments
 We have successfully built artifacts on the following environments: