Remove section on bootstrap branch, no longer relevant.

docs/releases.txt

@@ -12,21 +12,6 @@ is major, minor, or patch based on the scope of the changes in the
 release. Then, push the commits to the master branch. If tests pass,
 the release will be uploaded to PyPI (from the Python 3.5 tests).
 
-Bootstrap Branch
-----------------
-
-Setuptools has a bootstrap script (ez_setup.py), which is hosted in the
-repository in the ``bootstrap`` branch.
-
-Therefore, the latest bootstrap script can be retrieved by checking out
-that branch.
-
-The officially-published location of the bootstrap script is hosted on Python
-infrastructure (#python-infra on freenode) at https://bootstrap.pypa.io and
-is updated every fifteen minutes from the bootstrap branch. Sometimes,
-especially when the bootstrap script is rolled back, this
-process doesn't work as expected and requires manual intervention.
-
 Release Frequency
 -----------------