Fix #1046 - handle xsd as xml (#1067)

Author: moritzfl

internal/core/format.go

@@ -88,7 +88,7 @@ var FormatByExtension = map[string][]string{
 	`\.(?:swift)$`:     {".c", "code"},
 	`\.(?:ts|tsx)$`:    {".ts", "code"},
 	`\.(?:txt)$`:       {".txt", "text"},
-	`\.(?:xml)$`:       {".xml", "markup"},
+    `\.(?:xml|xsd)$`:   {".xml", "markup"},
 	`\.(?:yaml|yml)$`:  {".yml", "data"},
 	`\.(?:json)$`:      {".json", "data"},
 	`\.(?:toml)$`:      {".toml", "data"},

internal/lint/lint.go

@@ -197,7 +197,7 @@ func (l *Linter) lintFile(src string) lintResult {
 			err = l.lintMDX(file)
 		case ".rst":
 			err = l.lintRST(file)
-		case ".xml":
+        case ".xml", ".xsd":
 			err = l.lintXML(file)
 		case ".dita":
 			err = l.lintDITA(file)