src/vs/workbench/contrib/extensions/browser/extensionsWorkbenchService.ts/Extension/getReadme
class Extension:	getReadme(token: CancellationToken): Promise<string> {
		if (this.local && this.local.readmeUrl && !this.outdated) {
			return this.fileService.readFile(this.local.readmeUrl).then(content => content.value.toString());
		}

		if (this.gallery) {
			if (this.gallery.assets.readme) {
				return this.galleryService.getReadme(this.gallery, token);
			}
			this.telemetryService.publicLog('extensions:NotFoundReadMe', this.telemetryData);
		}

		if (this.type === ExtensionType.System) {
			return Promise.resolve(`# ${this.displayName || this.name}
**Notice:** This extension is bundled with Visual Studio Code. It can be disabled but not uninstalled.
## Features
${this.description}
`);
		}

		return Promise.reject(new Error('not available'));
	}