Update release documentation (open-telemetry#993)

* Update release docs

Clean up language and include directions to handle the Changelog during
a release.

* Fix grammar

RELEASING.md

@@ -1,12 +1,10 @@
 # Release Process
 
 ## Pre-Release
-Update go.mod for submodules to depend on the new release which will happen
-in the next step. This will create build failure for those who depend
-on the master branch instead or released version. But they shouldn't be
-depending on the master. So it is not a concern.
 
-1. Run the pre-release script. It creates a branch pre_release_<tag> to make the changes.
+Update go.mod for submodules to depend on the new release which will happen in the next step.
+
+1. Run the pre-release script. It creates a branch `pre_release_<new tag>` that will contain all release changes.
 
     ```
     ./pre_release.sh -t <new tag>
@@ -18,26 +16,42 @@ depending on the master. So it is not a concern.
     git diff master
     ```
 
-3. Push the changes to upstream.
+    This should have changed the version for all modules to be `<new tag>`.
 
-    ```
-    git push
-    ```
+3. Update the [Changelog](./CHANGELOG.md).
+   - Make sure all relevant changes for this release are included and are in language that non-contributors to the project can understand.
+       To verify this, you can look directly at the commits since the `<last tag>`.
+
+       ```
+       git --no-pager log --pretty=oneline "<last tag>..HEAD"
+       ```
+
+   - Move all the `Unreleased` changes into a new section following the title scheme (`[<new tag>] - <date of release>`).
+   - Update all the appropriate links at the bottom.
 
-4. Create a PR on github and merge the PR once approved.
+4. Push the changes to upstream and create a Pull Request on GitHub.
+    Be sure to include the curated changes from the [Changelog](./CHANGELOG.md) in the description.
 
 
 ## Tag
-Now create a new Tag on the commit hash of the changes made in pre-release step.
-Use the same tag as used in the pre-release step.
 
-1. Run the tag.sh script.
+Once the Pull Request with all the version changes has been approved and merged it is time to tag the merged commit.
+
+***IMPORTANT***: It is critical you use the same tag that you used in the Pre-Release step!
+Failure to do so will leave things in a broken state.
+
+***IMPORTANT***: [There is currently no way to remove an incorrectly tagged version of a Go module](https://github.com/golang/go/issues/34189).
+It is critical you make sure the version you push upstream is correct.
+[Failure to do so will lead to minor emergencies and tough to work around](https://github.com/open-telemetry/opentelemetry-go/issues/331).
+
+1. Run the tag.sh script using the `<commit-hash>` of the commit on the master branch for the merged Pull Request.
 
     ```
     ./tag.sh <new tag> <commit-hash>
     ```
 
-2. Push tags upstream. Make sure you run this for all sub-modules as well.
+2. Push tags to the upstream remote (not your fork: `github.com/open-telemetry/opentelemetry-go.git`).
+    Make sure you push all sub-modules as well.
 
     ```
     git push upstream <new tag>
@@ -46,15 +60,18 @@ Use the same tag as used in the pre-release step.
     ```
 
 ## Release
-Now create a release for the new `<new tag>` on github.
-The release body should include all the release notes in the Changelog for this release.
-Additionally, the `tag.sh` script generates commit logs since last release which can be used to suppliment the release notes.
+
+Finally create a Release for the new `<new tag>` on GitHub.
+The release body should include all the release notes from the Changelog for this release.
+Additionally, the `tag.sh` script generates commit logs since last release which can be used to supplement the release notes.
 
 ## Verify Examples
-After releasing run following script to verify that examples build outside of the otel repo.
-The script copies examples into a different directory and builds them.
+
+After releasing verify that examples build outside of the repository.
 
 ```
 ./verify_examples.sh
 ```
 
+The script copies examples into a different directory removes any `replace` declarations in `go.mod` and builds them.
+This ensures they build with the published release, not the local copy.