Update installation instructions for Go 1.17 onwards

Author: jlyonsmith

README.md

@@ -17,6 +17,8 @@ This directory contains directly usable tools installable via:
 
 ```
 go get periph.io/x/cmd/...
+# From Go 1.17 onwards use the following - see https://go.dev/doc/go-get-install-deprecation
+go install periph.io/x/cmd/...
 ```
 
 

codecov.yml

@@ -18,3 +18,10 @@ coverage:
       default:
         target: 60%
         threshold: 10%
+ignore:
+  - "README.md"
+  - "LICENSE"
+  - "CONTRIBUTORS"
+  - "CONTRIBUTING.md"
+  - "AUTHORS"
+  - "codecov.yml"