chore: move cli entrypoint to root

Author: omissis

.goreleaser.yaml

@@ -4,7 +4,7 @@ before:
   hooks:
     - go mod tidy
 builds:
-  - main: cmd/gojsonschema/main.go
+  - main: main.go
     env:
       - CGO_ENABLED=0
     goos:

README.md

@@ -24,7 +24,7 @@ This tool generates Go data types and structs that corresponds to definitions in
 
 ```shell
 $ go get github.com/atombender/go-jsonschema/...
-$ go install github.com/atombender/go-jsonschema/cmd/gojsonschema@latest
+$ go install github.com/atombender/go-jsonschema@latest
 ```
 
 * **Install with Brew**: To install with [Homebrew](https://brew.sh):