Salesforce Knowledge is available in Performance and Developer editions.
Salesforce Knowledge is available for an additional cost in Enterprise and Unlimited editions.
Users access articles from the Recent section of the Salesforce1 navigation menu. Look for Knowledge Article Versions in Salesforce1 for Android or Articles in the mobile browser app. To locate this item, it may be necessary to expand the Recent section by tapping Show More. Salesforce Knowledge is automatically included in the navigation menu as part of the Smart Search Items element. See “Salesforce1 Mobile App Navigation Menu” in the Salesforce Help for information about how the navigation menu is populated.