Add spec_urls for WebDriver commands (#23851)

diff --git a/webdriver/commands/GetElementText.json b/webdriver/commands/GetElementText.json
index 5f8c7ec..48197d0 100644
--- a/webdriver/commands/GetElementText.json
+++ b/webdriver/commands/GetElementText.json
@@ -3,6 +3,7 @@
     "commands": {
       "GetElementText": {
         "__compat": {
+          "spec_url": "https://w3c.github.io/webdriver/#get-element-text",
           "support": {
             "chrome": {
               "version_added": "65",