doc: fixed a few hiccups in README and maintainers doc

Signed-off-by: Frédéric BIDON <fredbi@yahoo.com>

Author: fredbi

README.md

@@ -27,6 +27,13 @@ go get github.com/go-openapi/errors
 ## Basic usage
 
 ```go
+const url = "https://www.example.com/#"
+
+errGeneric := New(401,"onvalid argument: %s", url)
+
+errNotFound := NotFound("resource not found: %s", url)
+
+errNotImplemented := NotImplemented("method: %s", url)
 ```
 
 ## Change log

docs/MAINTAINERS.md

@@ -144,7 +144,7 @@ Standard documentation:
 
 Reference documentation (released):
 
-* [godoc](https://pkg.go/dev/go-openapi/errors)
+* [godoc](https://pkg.go.dev/github.com/go-openapi/errors)
 
 ## TODOs & other ideas