fix: resolve multiple issues across Day 1, 2, 8, 14, 18, 22

[harshc01]

Hey! I went through some of the open issues and fixed a bunch of them in one go. Here's what I changed:

---

#807 + #758 — Day 1: Wrong comment on set/tuple (helloworld.py)

{9.8, 3.14, 2.7} is a set, curly braces give you a set not a tuple. The comment said # Tuple which is wrong and would confuse beginners. Fixed the comment and also added the actual tuple example with parentheses so both are shown side by side.

---

#808 — Day 14: That exercise question is JavaScript, not Python

Question 8 in Level 2 had arr.map(callback).filter(callback).reduce(callback) — that's JS method chaining. Python doesn't work like that, map/filter/reduce are standalone functions. I have replaced it with a proper Python description.

---

#775 + #792 — Day 2: int('10.6') crashes with ValueError

The example tried to do int(num_str) directly on '10.6' which just throws a ValueError. Also had the same variable assigned twice for no reason and int(num_int) on something that was already an int. Cleaned the whole thing up.

---

#760 — Day 22: Broken URL in exercise

The BU facts page link was using http:// and returning a 404. Just changed it to https://, the page is still up.

---

#749 — Day 18: re.match in the search syntax example

The syntax section for re.search was showing re.match(...) instead. Simple!

---

#731 — Day 8: Dictionaries are not "unordered" anymore

Calling dicts unordered is only true for Python 3.6 and below. Since 3.7 they maintain insertion order. Updated the definition to reflect that — also avoided just saying "ordered" since that implies sorting which isn't the case.

---

#721 — Day 8: is_marred typo

The person dictionary had is_marred instead of is_married in 6 different places, which also broke some of the code examples further down. I have fixed all of them.