Add release notes in preparation for next release

Many changes merged since the last release lack release notes. Since
we'll want to summarize them for the announcement anyway, we may as
well commit those summaries for posterity.

Change-Id: I56cda54cd9df781004462e95545a192302dd7bd4

releasenotes/notes/branch-author-selection-02d8652d12c4dd7a.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    A new ``gitreview.branchauthor`` option allows configuring the change
+    author (owner) name part of the autocreated branch name when downloading
+    changes.

releasenotes/notes/commit-hook-submodules-121f76901305ff98.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    The Change-Id generating commit hook is now installed into any detected Git
+    submodules, so that it will take effect when creating changes within a
+    submodule and not just in the parent repository.

releasenotes/notes/default-notopic-3f854006482616cd.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    A new ``gitreview.notopic`` configuration setting makes git-review always
+    behave as if the ``--notopic`` command line option was supplied.

releasenotes/notes/discontinue-draft-support-031e1fe3453ca839.yaml

@@ -0,0 +1,8 @@
+---
+deprecations:
+  - |
+    Not really a deprecation so much as a removal, Gerrit 2.15 (released in
+    2017) ceased providing a draft state for changes, and many large sites were
+    disabling support for it far earlier than that. As of now, git-review has
+    removed the ``-D`` and ``--draft`` options entirely, and so can no longer
+    push draft changes on old Gerrit deployments which still allowed them.

releasenotes/notes/drop-python27-support-37e1602a03d602ab.yaml

@@ -0,0 +1,11 @@
+---
+critical:
+  - |
+    As of this release, git-review no longer supports running under the Python
+    2.7 interpreter. The major version component has been increased
+    accordingly. Users wishing to use git-review with Python 2.7 can cap their
+    installations like ``pip install "git-review<2"``, though pip version 9 and
+    later will use python_requires package metadata to avoid installing
+    git-review on an unsupported interpreter. Future removal of support for
+    Python 3 minor versions will only result in a minor version increase for
+    corresponding git-review releases.

releasenotes/notes/git-credentials-bytes-6fcecd405dc4ed29.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Encoding was corrected for Git credentials, which was previously causing
+    HTTP authentication to fail under some Python 3 versions.

releasenotes/notes/preserve-local-edits-on-download-0f11c676e5516d9f.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Change download functions now preserve any unapplied local edits on the
+    branch when attempting to reset the worktree.

releasenotes/notes/push-no-follow-tags-3f366ecee85b508d.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    The ``--no-follow-tags`` option to ``git push`` is now used for all pushes,
+    so that git-review won't error when encountering a local tag which is
+    absent from Gerrit.