Gherkin syntax-highlighting in ReadMe files

Author: mdmintz

README.md

@@ -80,7 +80,7 @@ def test_mfa_login(sb):
 
 <p align="left">↘️ Example test with <b>behave-BDD</b> <a href="https://behave.readthedocs.io/en/stable/gherkin.html">Gherkin</a> structure. Runs with <code>behave</code>. (<a href="https://github.com/seleniumbase/SeleniumBase/blob/master/examples/behave_bdd/ReadMe.md">Learn more</a>)</p>
 
-```bash
+```gherkin
 Feature: SeleniumBase scenarios for the RealWorld App
 
     Scenario: Verify RealWorld App (log in / sign out)

examples/behave_bdd/ReadMe.md

@@ -144,7 +144,7 @@ def add_item_to_cart(context, item):
 
 🐝 A ``*.feature`` file could look like this:
 
-```bash
+```gherkin
 Feature: SeleniumBase scenarios for the Swag Labs App
 
     Background:
@@ -173,7 +173,7 @@ Feature: SeleniumBase scenarios for the Swag Labs App
 
 🐝 Here's another example of a ``*.feature`` file:
 
-```bash
+```gherkin
 Feature: SeleniumBase scenarios for the RealWorld App
 
     Scenario: Verify RealWorld App (log in / sign out)

help_docs/syntax_formats.md

@@ -523,7 +523,7 @@ features/
 
 A ``*.feature`` file might look like this:
 
-```bash
+```gherkin
 Feature: SeleniumBase scenarios for the RealWorld App
 
     Scenario: Verify RealWorld App (log in / sign out)
@@ -571,7 +571,7 @@ from seleniumbase.behave import steps  # noqa
 
 That will allow you to use lines like this in your ``*.feature`` files:
 
-```bash
+```gherkin
 ...
     Given Open "seleniumbase.io/realworld/login"
     And Clear Session Storage

integrations/behave/ReadMe.md

@@ -141,7 +141,7 @@ def add_item_to_cart(context, item):
 
 🐝 A ``*.feature`` file could look like this:
 
-```bash
+```gherkin
 Feature: SeleniumBase scenarios for the Swag Labs App
 
     Background:
@@ -170,7 +170,7 @@ Feature: SeleniumBase scenarios for the Swag Labs App
 
 🐝 Here's another example of a ``*.feature`` file:
 
-```bash
+```gherkin
 Feature: SeleniumBase scenarios for the RealWorld App
 
     Scenario: Verify RealWorld App (log in / sign out)