Remove the red text color from the polar-align instructions.

Small change to remove the red coloring from the help text that appears in the polar-alignment pages. The words that previously were 'red and bold' are changed to just 'bold'. I saw some criticism about the red text readability, and in retrospect I tend to agree. Also, it interferes with red-screen software.

Note: I kept the two words that were green and yellow colored, as they mirror the color of rendered lines on the image display.