Update securing-repositories.md

Author: andyblundell

practices/securing-repositories.md

@@ -10,7 +10,9 @@
 
 In line with [NCSC guidance](https://www.ncsc.gov.uk/collection/developers-collection/principles/protect-your-code-repository) it is important to secure your code repository.
 
-This guide describes our minimum set of requirements to secure & configure our Github repositories. This minimum set should be implemented alongside other relevant guidance which contribute to [security](security.md) as a whole. Please also see [Quality Checks](../quality-checks.md).
+This guide describes our minimum set of requirements to secure & configure our code repositories, with specific guidance for GitHub-based repositories.
+
+This minimum set of requirements should be implemented alongside other relevant guidance which contribute to [security](security.md) as a whole. Please also see [Quality Checks](../quality-checks.md).
 
 ## Access controls