Update image instructions for blog post template

[lillihart]

old:

• Add a few photos or other related graphics
  • Size to 768 x 512, 144dpi
  • for the Feature Image, if possible and if it looks good, add a 1 px border to the image with color Berkeley Blue, Hex 002676
  • Crop and adjust the lighting as needed
  • Ask for help if needed

new:

• Add a few photos or other related graphics
  • blog images - size to 768 wide
    • Crop and adjust the lighting as needed
  • for the Feature Image - use this Google Slide template to size the image to 768x512 and to add a blue border
  • hint: To download the images after they have been added to a google doc, navigate to File > Download > Web Page

[mnmnm22]

Updated it and waiting for review!