add cSpell configuration file

Author: smdn

.vscode/cspell.json

@@ -0,0 +1,40 @@
+// SPDX-FileCopyrightText: 2025 smdn <smdn@smdn.jp>
+// SPDX-License-Identifier: MIT
+//
+// cSpell Settings
+// https://marketplace.visualstudio.com/items?itemName=streetsidesoftware.code-spell-checker
+//
+{
+  // Version of the setting file.  Always 0.2
+  "version": "0.2",
+  // language - current active spelling language
+  "language": "en",
+  // words - list of words to be always considered correct
+  "words": [
+    "memberwise",
+    "munin",
+    "smdn",
+  ],
+  "ignoreWords": [
+    "dirtyconfig",
+    "netstandard",
+    "multigraph",
+    "vlabel"
+  ],
+  // flagWords - list of words to be always considered incorrect
+  // This is useful for offensive words and common spelling errors.
+  // For example "hte" should be "the"
+  "flagWords": [],
+  "ignorePaths": [
+    "**/bin",
+    "**/obj",
+    ".git",
+  ],
+  "enabledLanguageIds": [
+    "csharp",
+    "markdown",
+    "plaintext",
+    "xml",
+    "yaml"
+  ],
+}