Add High Level Documentation (#5665)

Add High Level Documentation (#5665)

* Add High Level Documentation

- Added image of overall architecture of project
- Added image with data flow through the pipeline
- Added Core Structure component
- Added and mapped non-functional requirements
- Updated revision history

* add overview of components
* add initial version of API secton
* add IR description
* add runtime behavior
* add structural description of IRs
* add compiler structure and behavioral description
* add structure diagram about nn runtime
* add constraints and scope items
* add Traceability Matrix
* add table of contents and items required by template
* add description about gray and white modules on component diagram
* update images to eliminate ambiguous interpretation
* change heading, rename nn Compute component
* break sections in more items
* bring back nnapi part
* rename NNFW IR into neurun IR and fix naming of other components
* fix formatting of subsystem description & abbreviations
* remove redundant item from compiler description
* fix typos and wording

Signed-off-by: Efimov Alexander <a.efimov@samsung.com>