Migrate default git branch from master to main (closes #86)

Last month, GitHub switched their default git branch from `master` to
`main`. So, if GitHub is doing it for their millions and millions of
repos and users, there are few good reasons not to for this repo.

    https://github.com/github/renaming

This commit changes all references of `master` to `main` in the Antora
site configuration. This commit is already pushed to a git branch,
`main`, on the council-docs repo. But this commit will be opened as a
Pull Request to the `master` branch.

**Do not merge without coordinating on the fedora-docs/docs-fp-o PR**.
If the builder is still configured to build onto `master`, well, that
obviously will not work. Please coordinate these changes simultaneously.

Closes #86. cc: @mattdm

Signed-off-by: Justin W. Flory (he/him) <git@jwf.io>

council/antora.yml

@@ -4,7 +4,7 @@ name: council
 # Title will be visible on the page.
 title: Fedora Council
 # If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "master" to a specific version.
-version: master
+version: main
 # We encourage you to name the index page as "index.adoc". If you absolutely have to use a different name, please reflect it here. You can ignore this field otherwise.
 start_page: ROOT:index
 # This lists all the menu definitions of your component.

council/modules/ROOT/pages/index.adoc

@@ -321,7 +321,7 @@ https://fedorahosted.org/council/ticket/13[Oct. 9th, 2014] and is in effect
 as of Nov. 26th, 2014. Any other significant changes will be noted here;
 smaller changes (minor wording or formating, etc., without impact on
 meaning) can be found in the
-https://pagure.io/Fedora-Council/council-docs/commits/master[git repository]
+https://pagure.io/Fedora-Council/council-docs/commits/main[git repository]
 for Council documents.
 
 2017-11-15: Update Diversity Advisor to Diversity Team Representative

council/modules/ROOT/pages/procedures/team_directory.adoc

@@ -16,7 +16,7 @@ However, presence in the directory may be used by other teams to evaluate fundin
 
 == Content
 
-Teams should list the following information in the format specified by https://pagure.io/Fedora-Council/council-docs/blob/master/f/engineering/modules/ROOT/partials/TEMPLATE_team_info.adoc[the template]:
+Teams should list the following information in the format specified by https://pagure.io/Fedora-Council/council-docs/blob/main/f/engineering/modules/ROOT/partials/TEMPLATE_team_info.adoc[the template]:
 
 * Team name
 * Team summary
@@ -51,7 +51,7 @@ Checks can be done at any time, but should be done around the branch date for ea
 The directory requires a file that contains the information about the team.
 The suggested naming convention is `NAME_team_info.adoc`, but any valid file name is acceptable.
 The file may be stored in the team's own documentation repository or in the https://pagure.io/Fedora-Council/council-docs/[council-docs repository].
-See the https://pagure.io/Fedora-Council/council-docs/blob/master/f/engineering/modules/ROOT/partials/TEMPLATE_team_info.adoc[example template] for format and structure.
+See the https://pagure.io/Fedora-Council/council-docs/blob/main/f/engineering/modules/ROOT/partials/TEMPLATE_team_info.adoc[example template] for format and structure.
 
 === Rendering the directory
 

engineering/antora.yml

@@ -5,8 +5,8 @@ name: engineering  # <---- PLEASE MODIFY
 # Title will be visible on the page.
 title: Engineering Teams # <---- PLEASE MODIFY
 
-# If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "master" to a specific version.
-version: master
+# If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "main" to a specific version.
+version: main
 
 # We encourage you to name the index page as "index.adoc". If you absolutely have to use a different name, please reflect it here. You can ignore this field otherwise.
 start_page: ROOT:index

mindshare/antora.yml

@@ -5,8 +5,8 @@ name: mindshare  # <---- PLEASE MODIFY
 # Title will be visible on the page.
 title: Mindshare Teams # <---- PLEASE MODIFY
 
-# If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "master" to a specific version.
-version: master
+# If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "main" to a specific version.
+version: main
 
 # We encourage you to name the index page as "index.adoc". If you absolutely have to use a different name, please reflect it here. You can ignore this field otherwise.
 start_page: ROOT:index

project/antora.yml

@@ -5,8 +5,8 @@ name: project
 # Title will be visible on the page.
 title: Fedora Project
 
-# If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "master" to a specific version.
-version: master
+# If you don't plan to have multiple versions of the docs (for example, to document multiple versions of some software), you can ignore this field. Otherwise, change "main" to a specific version.
+version: main
 
 # We encourage you to name the index page as "index.adoc". If you absolutely have to use a different name, please reflect it here. You can ignore this field otherwise.
 start_page: ROOT:index