Add clarification in README.md that Go 1.16+ required. (#651)

* fix: fix the multiple scan executions from pre-commit hook

* docs: add clarification note about Go version required\

Ref 646

Co-authored-by: dustin <dustinshimono@gmail.com>

README.md

@@ -58,6 +58,7 @@ docker run -v ${PWD}:/my-repo zricethezav/gitleaks:latest --path="/my-repo" [OPT
 ```
 
 ##### Go
+Go 1.16+ required.
 ```bash
 GO111MODULE=on go get github.com/zricethezav/gitleaks/v7
 ```