add cert screenshots for macosx

cert_instructions/macosx_cert.md

@@ -4,19 +4,32 @@
   * Go to "Devices"
   * In the "Download Certificate" section, click "Mac OS X"
   * In the file dialog, choose "Save File", as shown below
- 
 
-  * Open the "Keychain Access" app
+ <img src="macosx_screenshots/01_download_cert.png" alt="screenshot of download certificate dialog" height="500"/> 
+
+  * Open the "Keychain Access" app, you should see something like the screenshot below
+  
+ <img src="macosx_screenshots/02_keychain_access.png" alt="screenshot of Keychain Access app" height="500"/>
+
   * Select the "login" keychain from the "Keychains" list in the top-left panel
   * From the "File" menu, choose "Import Items...", as shown below
   
+ <img src="macosx_screenshots/03_import_items.png" alt="screenshot of 'import items' in Keychain Access app" height="500"/>
+
+  * In the file selection dialog, find the Certificate file that you downloaded earlier and click "Open"
+  * Right-click (or Control-Click) on the Certificate that you just added and choose "Get Info", as shown below
+  
+ <img src="macosx_screenshots/04_cert_get_info.png" alt="screenshot of 'Get Info' after adding certificate" height="500"/>
+
+  * Toggle the arrow next to the "Trust" section to expand it, and the top drop-down box which reads "When using this certificate:", select "Always Trust". The screenshot below is illustrative:
+  
+ <img src="macosx_screenshots/05_cert_trust.png" alt="screenshot of certificate dialog with 'Trust' section expanded" height="500"/>
+
+  * Close the Certificate info dialog.
+  * An authorization dialog will appear like the one shown below. Enter your Mac user name and password and click "Update Settings" to authorize the change.
+
+ <img src="macosx_screenshots/06_confirm_trust.png" alt="screenshot of dialog to confirm changes to certificate trust" height="500"/>
 
-  * Find the Certificate file that you downloaded earlier and click "Open"
-  * Right-click on the Certificate that you just added and choose "Get Info"
-  * Toggle the arrow next to the "Trust" section to expand it
-  * In the top drop-down box which reads "When using this certificate:", select "Always Trust"
-  * Close the Certificate info dialog
-  * An authorization dialog will appear. Enter your Mac user name and password and click "Update Settings" to authorize the change.
   * Close the "Keychain Access" application.
   * Congratulations! You have successfully installed your Bubble certificate!
   * NOTE: if you use the Firefox web browser, you must also separately [install your Bubble Certificate in Firefox](firefox_cert.md)