Sync code of conduct from cncf upstream

content/en/docs/contribute/advanced.md

@@ -136,7 +136,7 @@ The role of co-chair is one of service: co-chairs build contributor capacity, ha
 Responsibilities include:
 
 - Keep SIG Docs focused on maximizing developer happiness through excellent documentation
-- Exemplify the [community code of conduct](https://github.com/cncf/foundation/blob/master/code-of-conduct.md) and hold SIG members accountable to it
+- Exemplify the [community code of conduct](https://github.com/cncf/foundation/blob/main/code-of-conduct.md) and hold SIG members accountable to it
 - Learn and set best practices for the SIG by updating contribution guidelines
 - Schedule and run SIG meetings: weekly status updates, quarterly retro/planning sessions, and others as needed
 - Schedule and run doc sprints at KubeCon events and other conferences
@@ -147,7 +147,7 @@ Responsibilities include:
 
 To schedule and run effective meetings, these guidelines show what to do, how to do it, and why.
 
-**Uphold the [community code of conduct](https://github.com/cncf/foundation/blob/master/code-of-conduct.md)**:
+**Uphold the [community code of conduct](https://github.com/cncf/foundation/blob/main/code-of-conduct.md)**:
 
 - Hold respectful, inclusive discussions with respectful, inclusive language.
 

content/en/docs/contribute/localization.md

@@ -157,7 +157,7 @@ For example, for German the strings live in `data/i18n/de/de.toml`, and
 
 ### Localize the community code of conduct
 
-Open a PR against the [`cncf/foundation`](https://github.com/cncf/foundation/tree/master/code-of-conduct-languages) repository to add the code of conduct in your language.
+Open a PR against the [`cncf/foundation`](https://github.com/cncf/foundation/tree/main/code-of-conduct-languages) repository to add the code of conduct in your language.
 
 
 ### Setting up the OWNERS files

content/en/docs/contribute/review/reviewing-prs.md

@@ -27,7 +27,7 @@ Before reviewing, it's a good idea to:
 
 Before you start a review:
 
-- Read the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/master/code-of-conduct.md) and ensure that you abide by it at all times.
+- Read the [CNCF Code of Conduct](https://github.com/cncf/foundation/blob/main/code-of-conduct.md) and ensure that you abide by it at all times.
 - Be polite, considerate, and helpful.
 - Comment on positive aspects of PRs as well as changes.
 - Be empathetic and mindful of how your review may be received.