Implementing breadcrumbs

[sboldyreva]

Navigation enhancements:

• 2 new files added to add and generate breadcrumbs: docs/.vuepress/breadcrumbs.js and docs/.vuepress/enhanceApp.js
• Updated docs/.vuepress/config.js to include breadcrumb logic
• Updated docs/.vuepress/styles/index.styl for the breadcrumbs style
• Wiki pages updated to define the hierarchy for each file:
  • Define parent(1 level), grandparent (2 level), child (3 level)
  • For each 'hierarchy directory' definition in docs/.vuepress/breadcrumbs.js:
    • path - if there's path
    • linkable - true or false

Display examples: