Wiki: Improve introduction to Lua

[Kebap]

Brief summary of issue / Description of requested feature:

Supply basic examples for regular tasks (not necessarily Mudlet specific commands)

Reasons for adding feature:

People who only play games will have limited knowledge of coding in general and coding in Lua as well. The existing tutorials and API documentations seem dry and geared towards different audiences. Therefore, it would make sense to include at least some basic Lua coding examples in Mudlet's introduction page as well.

Expected result of feature

Examples include:

1. Conditions if-then-elseif-else
2. Loops of the usual kinds
3. Handling tables and meta-tables
4. Functions, parameters, returned values
5. String manipulations, mathmatics, etc.

Extra information, such as Mudlet version, operating system and ideas for how to solve / implement:

Add section to https://wiki.mudlet.org/w/Manual:Introduction with additional links to more detailed pages, just like the other sections in Mudlet's introduction page.