RFR: Section on sponsoring [v5]

[Jesper Wilhelmsson]

> Copied and updated the text from the old sponsoring page: https://openjdk.org/sponsor/
> The purpose is to have the sponsor link on the OpenJDK page lead here instead.
> 
> Also updated the contributing section with some parts taken from the old contributing page: https://openjdk.org/contribute/
> Again, the intention is to change the link on the OpenJDK page to lead here.

Jesper Wilhelmsson has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 11 additional commits since the last revision:

 - Merge branch 'contribute' of github.com:JesperIRL/guide into contribute
 - Added words
 - Fixed review comments
 - Updated text to cover more usecases.
 - Section on sponsoring
 - Reworked the entire section
 - Title change
 - Added words
 - Fixed review comments
 - Updated text to cover more usecases.
 - ... and 1 more: https://git.openjdk.org/guide/compare/0dc6f93f...e65a2585

-------------

Changes:
  - all: https://git.openjdk.org/guide/pull/97/files
  - new: https://git.openjdk.org/guide/pull/97/files/bd8c28b9..e65a2585

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=guide&pr=97&range=04
 - incr: https://webrevs.openjdk.org/?repo=guide&pr=97&range=03-04

  Stats: 239 lines in 11 files changed: 198 ins; 21 del; 20 mod
  Patch: https://git.openjdk.org/guide/pull/97.diff
  Fetch: git fetch https://git.openjdk.org/guide.git pull/97/head:pull/97

PR: https://git.openjdk.org/guide/pull/97