correct semantics of `series` and `closing` components, update relevant documentation

Description

Fixes: #21
changes series to opening
changes opening and closing components to aside rather than div elements
corrects a missing p within the child content of the closing example on the blog-post context.
updates documentation for opening and closing components to reflect correct naming, semantics, and structure.

Technical details

aside was chosen over a semantically classed div as it adds another layer of semantics which a div would not provide given that it is inherently semantically meaningless. article was also considered, but an article must be able to appropriately stand-alone as a separable piece of content which would add to a page, but not be devoid of inherent meaning if placed elsewhere (similar to a figure). This leaves an aside as the more appropriate semantic choice, with a descriptive class of opening and closing.

The <aside> HTML element represents a portion of a document whose content is only indirectly related to the document's main content. Asides are frequently presented as sidebars or call-out boxes. (mdn)

Tests

blog-post (preview): https://deploy-preview-47--vocabulary-docs.netlify.app/specimen/contexts/blog-post.html (see orange opening at top, blue closing at bottom)
opening docs (preview): https://deploy-preview-47--vocabulary-docs.netlify.app/#opening-summary-block
closing docs (preview): https://deploy-preview-47--vocabulary-docs.netlify.app/#closing-summary-block

Checklist

[ ] My pull request has a descriptive title (not a vague title like Update index.md).
[x] My pull request targets the default branch of the repository (main or master).
[x] My commit messages follow best practices.
[x] My code follows the established code style of the repository.
[ ] I added or updated tests for the changes I made (if applicable).
[x] I added or updated documentation (if applicable).
[x] I tried running the project locally and verified that there are no visible errors.

Developer Certificate of Origin

For the purposes of this DCO, "license" is equivalent to "license or public domain dedication," and "open source license" is equivalent to "open content license or public domain dedication."

Developer Certificate of Origin

``` Developer Certificate of Origin Version 1.1 Copyright (C) 2004, 2006 The Linux Foundation and its contributors. 1 Letterman Drive Suite D4700 San Francisco, CA, 94129 Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Developer's Certificate of Origin 1.1 By making a contribution to this project, I certify that: (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or (b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or (c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it. (d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved. ```

Name	Link
Latest commit	821a005c53eb8dd1bbc60e50b3723dd8fc5febec
Latest deploy log	https://app.netlify.com/sites/vocabulary-docs/deploys/6685ac9616eae50008e0c6cb
Deploy Preview	https://deploy-preview-47--vocabulary-docs.netlify.app
Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

creativecommons / vocabulary