Create string-manipulation.html

section about string methods

Create multidimensional-lists.html

add section about multidimensional lists

add bigger font to all pages

change font to be more readable in additional pages

change fonts with more readable ones

add lists as stacks and queues

add information about lists as stacks and queues

Update index.html

Create game-development.html

Update index.html

Update index.html

Create gui-programming.html

Create cybersecurity.html