Default branch rename in docs

Author: jvalkeal

docs/src/reference/asciidoc/appendix-distributedpaper.adoc

@@ -80,7 +80,7 @@ Jepsen tests in the following environment:
   events and check particular state machine statuses.
 
 All Jepsen tests for `Spring Distributed Statemachine` are available from
-https://github.com/spring-projects/spring-statemachine/tree/master/jepsen/spring-statemachine-jepsen[Jepsen
+https://github.com/spring-projects/spring-statemachine/tree/main/jepsen/spring-statemachine-jepsen[Jepsen
 Tests.]
 
 === Generic Concepts

docs/src/reference/asciidoc/sm-examples.adoc

@@ -64,7 +64,7 @@ project's `build/libs` directory.
 
 NOTE: The filenames for the jars to which we refer in this section are populated during a
 build of this document, meaning that, if you build samples from
-master, you have files with a `BUILD-SNAPSHOT` postfix.
+main, you have files with a `BUILD-SNAPSHOT` postfix.
 
 include::sm-examples-turnstile.adoc[]
 include::sm-examples-turnstilereactive.adoc[]