fix(pagination): correct pagination props/slots/event docs and fix ellipsis slot

[jacobmllr95]

Description of Pull Request:

This PR corrects the <b-pagination> docs about props, slots and events.

Ref: #2655.

PR checklist:

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Enhancement to an existing feature
• ARIA accessibility
• Documentation update
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact:

The PR fulfills these requirements:

• It's submitted to the dev branch, not the master branch
• When resolving a specific issue, it's referenced in the PR's title (i.e.
  fixes #xxxx[,#xxxx], where "xxxx" is the issue number)
• The PR should address only one issue or feature. If adding multiple features or fixing a bug
  and adding a new feature, break them into separate PRs if at all possible.
• PR titles should following the
  Conventional Commits naming convention (i.e.
  "fix(alert): not alerting during SSR render", "docs(badge): Updated pill examples, fix typos",
  "chore: fix typo in docs", etc). This is very important, as the CHANGELOG is generated
  from these messages.

If new features/enhancement/fixes are added or changed:

• Includes documentation updates (including updating the component's package.json for slot and
  event changes)
• New/updated tests are included and passing (if required)
• Existing test suites are passing
• The changes have not impacted the functionality of other components or directives
• ARIA Accessibility has been taken into consideration (does it affect screen reader users or
  keyboard only users? clickable items should be in the tab index, etc)

If adding a new feature, or changing the functionality of an existing feature, the PR's
description above includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a
  suggestion issue first and wait for approval before working on it)

[codecov]

Codecov Report

Merging #2699 into dev will not change coverage.
The diff coverage is n/a.

@@         Coverage Diff          @@
##            dev   #2699   +/-   ##
====================================
  Coverage    74%     74%           
====================================
  Files       173     173           
  Lines      3201    3201           
  Branches    939     939           
====================================
  Hits       2369    2369           
  Misses      610     610           
  Partials    222     222

Impacted Files	Coverage Δ
src/mixins/pagination.js	68.58% <ø> (ø)	⬆️

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