[DOC/WEB]: Resolving 'Getting started' URL ambiguity in pandas.io(Issue #32307)
The Following goals are being accomplished in this PR:
- [x] Having the navigation bar's 'Getting Started' link point to `/docs/getting_started/index.html` from `/getting_started.html`
- [x] Removing the redundant markup `pandas/web/pandas/getting_started.md`.
<!--- [x] Adding above redirecting information in `pandas/doc/redirect.csv`.-->

#32307 
