Created article about dictionaries

[ProgramCrafter]

Why is it important?

This article makes it written knowledge that dictionaries can have limited amount of key-value pairs and tend to make contract run out of gas if a large number of updates is made. Article also gives some information about other types of maps (according to other information sources available; prefix dictionaries don't have any, and trying to reverse-engineer them has an inconclusive results).

Related Issue

ton-society/grants-and-bounties#455

[reveloper]

@ProgramCrafter, you've done a great job for our docs, thank you!

I have several suggestions on improvements collected from the developer community, could you add information according to these comments?

1. Overall, the article is correctly written—the only thing I would add is that the @wallet bot's issue was primarily with the unlimited number of loop iterations, and the hashmap updates just made these iterations quite costly. Even without the hashmap, you might exceed the gas limit with an unlimited cycle. (@akifoq)

2. Could you add an example in the form of a cell dump showing what the map looks like inside? For instance, a dict int 256 with 3 different keys in it. (@xssnick)

[reveloper]

@ProgramCrafter, thank you!