refactor(commands): separate commands and its core into two folders (#32)

- I think it would be better if one for commands only, one for the spec
handling core logic so people won't be confused by the core logic inside
the commands folder (cleaner I guess)
- Regen docs

commands/rust/dprint.go

@@ -1,14 +1,14 @@
 package rust
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "dprint",
 		Description: "Prints the help of the given subcommand(s)",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "init", Description: "Initializes a configuration file in the current directory"},
 			{Name: "fmt", Description: "Formats the source files and writes the result to the file system"},
 			{Name: "check", Description: "Checks for any files that haven't been formatted"},
@@ -19,7 +19,7 @@ func init() {
 			{Name: "clear-cache", Description: "Deletes the plugin cache directory"},
 			{Name: "license", Description: "Outputs the software license"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--excludes", Description: "A pluggable and configurable code formatting platform written in Rust"},
 			{Name: "--diff", Description: "Outputs a check-like diff of every formatted file"},
 			{Name: "--stdin", Description: "Checks for any files that haven't been formatted"},