Changed the level 4 heading and added extra info

Changed the level 4 heading of purpose paragraph to level 6. Added additional section about Goals and Future plans of the project. The title of this section is in level 3 heading. Then, added bullet list of goals. Goals achieved are marked with (Done) in level 6 heading.
Corrected the (Done) written in level 6 heading

Added an extra space after the last pound of level 6 heading for (Done). Thus making this (Done) appear as level 6 heading now.
Added strike-through and added extra information

Removed the level 6 heading for (Done). Now using strike-through to mark the completed task in goals and future plan section. Gave the addition info about what strike-through means (below the heading of this section).
Corrected the spelling of finally 

Previous: Finaly
Now: Finally 
In goals and future plan section.
Merge pull request #1 from a8h1nay/doc-edit

Documentation editing and added extra info