Revised contributing.md, edited docs (#1951)

* Added Overview page

* Revised Getting Started page

* Minor revision

* Edited readme, minor modifications to docs

* Removed sweep.yaml, .devcontainer, .ergomake

* Moved security.md to .github, added contributing.md

* changes as per code review

* updated contributing.md

* fixed broken links & added missing links in doc, improved structure

* fixed link in wsl setup

* fixed server link, added https cloning in yarn-setup

docs/.gitignore

@@ -18,3 +18,5 @@
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
+
+package-lock.json