Added a section on UX concepts

[friste]

Three topics were touched on: accessibility, hierarchy, learnability, described briefly to give an overview with accompanying resources linked for more in-depth reading

[lmg8]

These are very organized and detailed additions to the user experience concept! There's just one small spelling mistake that needs to be fixed and this should be good to merge.

Edit: Can you add the new section on the README.md? This will make it easier for future contributors to see a breakdown of the topics covered in the repo.

[lmg8]

Suggested change

Accessibility is a concept that encapsulates one central idea: to allow all users to easily enjoy and use applications. In common usage, it can refer to users with temporary or permanent disabilities (visual, motor, auditory, etc.), but is broader than this, referring also to overall robustness and operability (i.e. is the workflow too complicated? Can multiple devices access the application, if it is a web application?). Consideration for varying degrees of ability is fundamental to design—a product should reach as wide of an audience as possible. Oftentimes, accesibility considerations lead to unintended benefits. For example, providing closed captioning on web video content can improve SEO indexing.

Accessibility is a concept that encapsulates one central idea: to allow all users to easily enjoy and use applications. In common usage, it can refer to users with temporary or permanent disabilities (visual, motor, auditory, etc.), but is broader than this, referring also to overall robustness and operability (i.e. is the workflow too complicated? Can multiple devices access the application, if it is a web application?). Consideration for varying degrees of ability is fundamental to design—a product should reach as wide of an audience as possible. Oftentimes, accessibility considerations lead to unintended benefits. For example, providing closed captioning on web video content can improve SEO indexing.