Merge branch 'docs' into 'dev'

Add final documenttion

See merge request bohacfr2/apo-sem!2

docs: add final text viewer and file browser diagrams

docs: add block diagrams for image viewer and text viewer

docs: finish user manual documentation

docs: add readme with documentation info

docs: add doxygen config

refactor: add gitignore to docs

docs: move doc to user manual

docs: add date

docs: make appropriate code modifiers

docs: add manual and and compilation documentation

docs: add first description of image viewer