Update automation to use main as default branch (#629)

.github/workflows/reference_linter.yaml

@@ -2,13 +2,13 @@ name: Lint Reference Files
 on:
   push:
     branches:
-      - master
+      - main
     paths:
       - '.github/linter_config.yml'
       - 'locale/en/**.ftl'
   pull_request:
     branches:
-      - master
+      - main
     paths:
       - '.github/linter_config.yml'
       - 'locale/en/**.ftl'

.github/workflows/test.yaml

@@ -2,7 +2,7 @@ name: Tests
 on:
   push:
     branches:
-      - master
+      - main
     paths:
       - 'locale/**/*.po'
   workflow_dispatch:

README.md

@@ -9,7 +9,7 @@ This repo (abbreviated as "L10N" in this README) contains all translated/transla
 
 The string localization is managed in [Pontoon](https://pontoon.mozilla.org/projects/firefox-accounts/) and it pushes changes anytime it likes.
 
-On a regular basis (currently once a week) a [cron job runs](https://github.com/mozilla/fxa-content-server-l10n/blob/master/.github/workflows/l10n_extract.yaml) to extract all the strings from SOURCE and open a PR to merge them into this repository. Someone from the localization team will review that PR for any strings that are confusing to localize and, if there aren't any problems, will merge it. At that point Pontoon sees the changes and strings can be localized from the Pontoon interface.
+On a regular basis (currently once a week) a [cron job runs](https://github.com/mozilla/fxa-content-server-l10n/blob/main/.github/workflows/l10n_extract.yaml) to extract all the strings from SOURCE and open a PR to merge them into this repository. Someone from the localization team will review that PR for any strings that are confusing to localize and, if there aren't any problems, will merge it. At that point Pontoon sees the changes and strings can be localized from the Pontoon interface.
 
 The extraction process can also be triggered manually from [here](https://github.com/mozilla/fxa-content-server-l10n/actions/workflows/l10n_extract.yaml).