feat: Add option to set default branch (#164)

* Add set default branch to Master configuration option

Author: abeatrix

README.md

@@ -27,6 +27,7 @@ This extension contributes the following settings:
 
 - `sourcegraph.url`: The Sourcegraph instance to use. Specify your on-premises Sourcegraph instance here, if applicable.
 - `sourcegraph.remoteUrlReplacements`: Object, where each `key` is replaced by `value` in the remote url.
+- `sourcegraph.defaultBranch`: String to set the name of the default branch. Always open files in the default branch.
 
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