DOC: Update link and description of the Spyder IDE in Ecosystem docs
Over the past few years, [Spyder](https://docs.spyder-ide.org/), a PyQt-based open source Python IDE focused on data science (comparable to MATLAB and Rstudio, but developed by community volunteers instead of a for-profit company), has incorporated a deep swath of ``pandas``-specific features and integration. We've also set up a new, modern website for the project, and a new documentation site as well explaining these, which should be linked to instead of the current one.

Accordingly, this PR does a few simple things, split into separate commits to make it easy to modify or revert any of the changes if undesired:

* It updates the Spyder URL to point to our new main website, in HTTPS
* It uses a more up to date one-liner description of Spyder itself, and principally focuses on a greatly expanded list of ways Spyder directly interacts with pandas and offers tools for working with Series and DataFrame objects.
    * As part of this, it embeds links to our new modern, online documentation that describes how these features work, for users to easily reference
* It also cleans up a few stray trailing spaces present in the Ecosystem docs (I can revert this if undesired)

I included a fair amount of detail in the different distinct ways Spyder interacts with pandas objects and the specific features it offers when working with such, but if you think its too long I can cut down the central paragraph accordingly; just let me know and I'll do it promptly.

Thanks!