DOC: Fix reference to action method to match BaseBot.

Author: hhslepicka

docs/bot.md

@@ -14,7 +14,7 @@ from botcity.web import WebBot
 
 
 class Bot(WebBot):
-    def action(self, execution):
+    def action(self, execution=None
         # Configure whether or not to run on headless mode
         self.headless = False
 

docs/intro.md

@@ -55,7 +55,7 @@ from botcity.web import WebBot, Browser
 
 
 class Bot(WebBot):
-    def action(self, execution):
+    def action(self, execution=None):
         # Configure whether or not to run on headless mode
         self.headless = False
 
@@ -82,7 +82,7 @@ from botcity.web import WebBot, Browser
 
 
 class Bot(WebBot):
-    def action(self, execution):
+    def action(self, execution=None):
         # Configure whether or not to run on headless mode
         self.headless = False
 
@@ -126,7 +126,7 @@ from botcity.web.browsers.chrome import default_options
 #from botcity.web.browsers.firefox import default_options
 
 class Bot(WebBot):
-    def action(self, execution):
+    def action(self, execution=None):
         # Configure whether or not to run on headless mode
         self.headless = False