Add hackthissite and spelling corrections in CTF category (#5643)

* Add GNU Emacs refcard to more/free-programming-cheatsheets.md file under ide/editors category

* Add alphabetical order and PDF indication for the adding emacs refcard

* Added PDF indication

* Add HackThisSite in CTF and corrected address spelling

* Removed slash from the end of the URL

more/problem-sets-competitive-programming.md

@@ -47,13 +47,14 @@
 
 ### Capture the flag
 
-* [CTFlearn](https://ctflearn.com) (email adress *requested*)
-* [Google Ctf](https://capturetheflag.withgoogle.com) (email adress *requested*)
-* [Hacker101](https://ctf.hacker101.com) (email adress *requested*)
-* [Hackthebox](https://www.hackthebox.eu) (email adress *requested*)
+* [CTFlearn](https://ctflearn.com) (email address *requested*)
+* [Google Ctf](https://capturetheflag.withgoogle.com) (email address *requested*)
+* [Hacker101](https://ctf.hacker101.com) (email address *requested*)
+* [Hackthebox](https://www.hackthebox.eu) (email address *requested*)
+* [HackThisSite](https://www.hackthissite.org) (email address *requested*)
 * [Overthewire Wargames fungame to practice CTF](https://overthewire.org/wargames/bandit)
-* [Picoctf](https://picoctf.org/resources) (email adress *requested*)
-* [TryHackMe](https://tryhackme.com) (email adress *requested*)
+* [Picoctf](https://picoctf.org/resources) (email address *requested*)
+* [TryHackMe](https://tryhackme.com) (email address *requested*)
 
 
 ### Data science