Rename bazel_skylib default branch to main.

See https://github.com/bazelbuild/bazel-skylib/branches and
https://github.com/bazelbuild/bazel-skylib/issues/281.

RELNOTES: None.
PiperOrigin-RevId: 368882757
diff --git a/site/docs/configurable-attributes.md b/site/docs/configurable-attributes.md
index 07b5fb2..18091ed 100644
--- a/site/docs/configurable-attributes.md
+++ b/site/docs/configurable-attributes.md
@@ -455,9 +455,9 @@
 ### <a name="selects-with-or"></a>`selects.with_or`
 
 The
-[with_or](https://github.com/bazelbuild/bazel-skylib/blob/master/docs/selects_doc.md#selectswith_or)
+[with_or](https://github.com/bazelbuild/bazel-skylib/blob/main/docs/selects_doc.md#selectswith_or)
 macro in [Skylib](https://github.com/bazelbuild/bazel-skylib)'s
-[`selects`](https://github.com/bazelbuild/bazel-skylib/blob/master/docs/selects_doc.md)
+[`selects`](https://github.com/bazelbuild/bazel-skylib/blob/main/docs/selects_doc.md)
 module supports `OR`ing conditions directly inside a `select`:
 
 ```python
@@ -479,9 +479,9 @@
 
 
 The
-[config_setting_group](https://github.com/bazelbuild/bazel-skylib/blob/master/docs/selects_doc.md#selectsconfig_setting_group)
+[config_setting_group](https://github.com/bazelbuild/bazel-skylib/blob/main/docs/selects_doc.md#selectsconfig_setting_group)
 macro in [Skylib](https://github.com/bazelbuild/bazel-skylib)'s
-[`selects`](https://github.com/bazelbuild/bazel-skylib/blob/master/docs/selects_doc.md)
+[`selects`](https://github.com/bazelbuild/bazel-skylib/blob/main/docs/selects_doc.md)
 module supports `OR`ing multiple `config_setting`s:
 
 ```python
@@ -522,7 +522,7 @@
 
 If you need a `select` branch to match when multiple conditions match, use the
 [Skylib](https://github.com/bazelbuild/bazel-skylib) macro
-[config_setting_group](https://github.com/bazelbuild/bazel-skylib/blob/master/docs/selects_doc.md#selectsconfig_setting_group):
+[config_setting_group](https://github.com/bazelbuild/bazel-skylib/blob/main/docs/selects_doc.md#selectsconfig_setting_group):
 
 ```python
 config_setting(