Question marks in titles, in particular those beginning 'How to ...'

In regards to:

How to ease Afghanistan’s progress in cricket

Is it grammatical, if we don't put question mark in questions of titles? I think this blog title should have been like this:

How to ease Afghanistan’s progress in cricket?

These are titles and thus do not necessarily follow standard grammatical rules, so don't let the absence of punctuation fool you. As to your suggested edit, questions simply do not start with how to. What this title is saying is that what follows will be instructions about how one would go about easing Afghanistan's progress. It's a short description of the document. If you wanted to make it into a complete sentence, you could add the implied information:

In this blog post, I will show you how to ease Afghanistan’s progress in cricket.

Now, when comparing

Election rigging 101: How to steal a mandate

and

Elections 101: What is the ECP and what does it do on election day?

you're comparing two different styles of titles. First, ignore the parts that come before the colons; they simply define the general topic. In the first example, again, you have a title that begins with how to indicating that the document consists of instructions. It will tell you how to steal a mandate.

In the second example, the title is a question. In this case the title gives you the question that the document will answer. What follows is the answer to that question.

It's up to the author as to how they want to phrase their title. You could certainly rephrase both of these to swap styles resulting in:

Election rigging 101: How does one steal a mandate?
Elections 101: The ECP and what it does on election day

But, again, this is a matter of style and not grammar.