feat(docs): add keymap upgrader

Added a documentation page with a script that upgrades deprecated key
codes and behaviors to their replacements.

Fixes #299

docs/src/docusaurus-tree-sitter-plugin/index.js

@@ -0,0 +1,39 @@
+module.exports = function () {
+  return {
+    configureWebpack(config, isServer) {
+      let rules = [];
+
+      // Tree-sitter is only used for client-side code.
+      // Don't try to load it on the server.
+      if (isServer) {
+        rules.push({
+          test: /web-tree-sitter/,
+          loader: "null-loader",
+        });
+      } else {
+        // web-tree-sitter has a hard-coded path to tree-sitter.wasm,
+        // (see https://github.com/tree-sitter/tree-sitter/issues/559)
+        // which some browsers treat as absolute and others as relative.
+        // This breaks everything. Rewrite it to always use an absolute path.
+        rules.push({
+          test: /tree-sitter\.js$/,
+          loader: "string-replace-loader",
+          options: {
+            search: '"tree-sitter.wasm"',
+            replace: '"/tree-sitter.wasm"',
+            strict: true,
+          },
+        });
+      }
+
+      return {
+        // web-tree-sitter tries to import "fs", which can be ignored.
+        // https://github.com/tree-sitter/tree-sitter/issues/466
+        node: {
+          fs: "empty",
+        },
+        module: { rules },
+      };
+    },
+  };
+};