update dev readme

README-DEV.md

@@ -3,7 +3,7 @@ Release Steps:
 - with no staged commits and a clean status...
 - meld a summary of `git log $(git tag --sort version:refname | tail -n 1)..HEAD --oneline` (all commits since last tag) with whatever hash with `[4.2.3]` in changelog
 - commit, push
-- `mkvirtualenv releasetest`
+- make a virtual environmentl and activate
 - check that `pip install .` and `python -c "import pyamg; pyamg.test()"` pass (outside source directory)
 - remove untracked files `git clean -xdf`
 - the following can be done with a pre-release, `v4.2.3-alpha.6`, for testing.  It will not become the default on pypi and `gh release create` can be marked with `--prerelease` (below)