docs: Address an upcoming violation of markdownlint rule MD050/strong-style.

[DavidAnson]

This file (and only this file in the repo) uses both __ and ** to create a strong emphasis. This change makes the file consistent by changing the single instance of __ to **. The current version of markdownlint and an upcoming version of markdownlint-cli do/will flag this violation. The new rule can be disabled, but resolving it in this case is trivial.

More info: https://github.com/DavidAnson/markdownlint/blob/main/doc/Rules.md#md050

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "X" next to an item)

[x] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofix to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

What changes did you make? (Give an overview)

See above/commit message.

Is there anything you'd like reviewers to focus on?

Check the word "not" is still strongly emphasized and the use of strong emphasis in the file is uniform.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ David Anson (de0a2fc)

[eslint-github-bot]

Hi @DavidAnson!, thanks for the Pull Request

The first commit message isn't properly formatted. We ask that you update the message to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by running git commit --amend, editing your commit message, and then running git push -f to update this pull request.

Read more about contributing to ESLint here

[eslint-github-bot]

Hi @DavidAnson!, thanks for the Pull Request

The first commit message isn't properly formatted. We ask that you update the message to match this format, as we use it to generate changelogs and automate releases.

• The length of the commit message must be less than or equal to 72

To Fix: You can fix this problem by running git commit --amend, editing your commit message, and then running git push -f to update this pull request.

Read more about contributing to ESLint here

[DavidAnson]

I updated the commit message once to add a prefix due to commit-message failing. It looks like it's still unhappy, perhaps the length is too long? Reviewers, please feel free to remove any part of the commit message you do not feel is useful or let me know how you'd like it changed - I've tried to be clear without leaving out context. Thanks.

[aladdin-add]

LGTM, thanks!

[eslint-github-bot]

Hi @DavidAnson!, thanks for the Pull Request

The first commit message isn't properly formatted. We ask that you update the message to match this format, as we use it to generate changelogs and automate releases.

• The length of the commit message must be less than or equal to 72

To Fix: You can fix this problem by running git commit --amend, editing your commit message, and then running git push -f to update this pull request.

Read more about contributing to ESLint here

[snitin315]

LGTM, thank you.

[nzakas]

LGTM. Thanks!