Removing a broken link in the README

The README has a broken link to the `problem.csv` file
so I removed that link and instead just noted that
an example of that file is shown below. This really
shouldn't affect the overall readability of the problem
description, but if anyone sees an issue with it let
me know.

I also added a note that mentions a possible CSV row
that often will break custom CSV parsers to encourage
devs to look into the `encoding/csv` package in Go.

Fixes gophercises#20

README.md

@@ -12,7 +12,7 @@ This exercise is broken into two parts to help simplify the process of explainin
 
 Create a program that will read in a quiz provided via a CSV file (more details below) and will then give the quiz to a user keeping track of how many questions they get right and how many they get incorrect. Regardless of whether the answer is correct or wrong the next question should be asked immediately afterwards.
 
-The CSV file should default to [problems.csv](problems.csv), but the user should be able to customize the filename via a flag.
+The CSV file should default to `problems.csv` (example shown below), but the user should be able to customize the filename via a flag.
 
 The CSV file will be in a format like below, where the first column is a question and the second column in the same row is the answer to that question.
 
@@ -36,6 +36,8 @@ You can assume that quizzes will be relatively short (< 100 questions) and will
 
 At the end of the quiz the program should output the total number of questions correct and how many questions there were in total. Questions given invalid answers are considered incorrect.
 
+**NOTE:** *CSV files may have questions with commas in them. Eg: `"what 2+2, sir?",4` is a valid row in a CSV. I suggest you look into the CSV package in Go and don't try to write your own CSV parser.*
+
 ### Part 2
 
 Adapt your program from part 1 to add a timer. The default time limit should be 30 seconds, but should also be customizable via a flag.