Remove extra backtick in install step

This just removes the extra back in the `go install` step. Helps people (like me) that just copy paste blindly into a Makefile or into the cmdline!

Author: srizzling

README.md

@@ -405,7 +405,7 @@ required = [
 ```
 In your CI scripts, install the vendored `golangci-lint` like this:
 ```bash
-go install ./vendor/github.com/golangci/golangci-lint/cmd/golangci-lint/`
+go install ./vendor/github.com/golangci/golangci-lint/cmd/golangci-lint/
 ```
 Vendoring `golangci-lint` saves a network request, potentially making your CI system a little more reliable.