chore(python): rename default branch to main (#170)

Source-Link: googleapis/synthtool@5c0fa62
Post-Processor: gcr.io/repo-automation-bots/owlbot-python:latest@sha256:0ffe3bdd6c7159692df5f7744da74e5ef19966288a6bf76023e8e04e0c424d7d

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: gcf-owl-bot[bot]

.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:1456ea2b3b523ccff5e13030acef56d1de28f21249c62aa0f196265880338fa7
+  digest: sha256:0ffe3bdd6c7159692df5f7744da74e5ef19966288a6bf76023e8e04e0c424d7d

CONTRIBUTING.rst

@@ -113,9 +113,9 @@ Coding Style
    export GOOGLE_CLOUD_TESTING_BRANCH="main"
 
   By doing this, you are specifying the location of the most up-to-date
-  version of ``python-error-reporting``. The the suggested remote name ``upstream``
-  should point to the official ``googleapis`` checkout and the
-  the branch should be the main branch on that remote (``main``).
+  version of ``python-error-reporting``. The
+  remote name ``upstream`` should point to the official ``googleapis``
+  checkout and the branch should be the default branch on that remote (``main``).
 
 - This repository contains configuration for the
   `pre-commit <https://pre-commit.com/>`__ tool, which automates checking

docs/conf.py

@@ -76,7 +76,7 @@
 # The encoding of source files.
 # source_encoding = 'utf-8-sig'
 
-# The main toctree document.
+# The root toctree document.
 root_doc = "index"
 
 # General information about the project.