Update date of midterm reflections on home

[jesings]

Since we have decided on the date that the midterm reflections will be (Mar 27), then this date should be put in the syllabus under the midterm exam/reflections part of the important dates section of the home page (index.html)

[rs1dev]

I can work on this.

[joannakl]

@rs1dev Go ahead. You may also add the date for the final reflections. It is posted on the CS department website.

[rs1dev]

70 made a PR