[FEATURE] Update README.md -> Adds list of algorithms separated by topic and in increasing difficulty

[omonimus1]

Detailed Description

It could be useful improve the content of the README.md file adding:

• Logo and a link to the forum room of the community.
• List of all the algorithms shown in different tables, according to the topic, for example:

Sorting
Algorithm 1
Algorithm 2

Searching
Algorithm 1
Algorithm 2

Context

• Listing all the algorithms in increasing difficulty order will be helpful for students and beginners

[kvedala]

Great point.

1. Regarding list of algorithms and organization: Please check the new documentation website:
   https://thealgorithms.github.io/C-Plus-Plus
   and its "Files" tab.
2. The link to the forum is provided in the ReadMe - it is the Gitter link shown as a badge.

Would that address the above concerns?

[kvedala]

Feel free to reopen the issue if you think this is not addressed and any suggestions as to why you think it is not fixed would be helpful.