docs: analyse branch or MR commits only

  # If set, forward console messages to terminal

README.md

@@ -3,9 +3,9 @@
 This project implements a GitLab CI/CD template to detect and prevent hardcoded secrets in your 
 Git repository with [Gitleaks](https://github.com/zricethezav/gitleaks/wiki).
 
-When run on the master branch, Gitleaks will audit all commits from all branches.
+When run on merge requests, Gitleaks will run a quick analysis of added commits (i.e. the diff).
 
-When run on other branches, Gitleaks will run a quick analysis on the current branch.
+When run on branches, Gitleaks will run an analysis of all commits in the branch.
 
 ## Usage