extensions/markdown-language-features/src/features/workspaceSymbolProvider.ts/VSCodeWorkspaceMarkdownDocumentProvider/getAllMarkdownDocuments
class VSCodeWorkspaceMarkdownDocumentProvider:	async getAllMarkdownDocuments() {
		const resources = await vscode.workspace.findFiles('**/*.md', '**/node_modules/**');
		const docs = await Promise.all(resources.map(doc => this.getMarkdownDocument(doc)));
		return docs.filter(doc => !!doc) as SkinnyTextDocument[];
	}