fix: Change "Usage" heading in README to all caps (#1180)

#### Details
This is updating the text in the README for the Usage section to now
show "USAGE".
<!-- Usually a sentence or two describing what the PR changes -->

##### Motivation
Triggering a build to confirm that the new GH token is being consumed
properly
<!-- This can be as simple as "addresses issue #123" -->

##### Context
Quarterly DRI rotation
<!-- Are there any parts that you've intentionally left out-of-scope for
a later PR to handle? -->

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tradeoffs did you consider? -->

#### Pull request checklist
<!-- If a checklist item is not applicable to this change, write "n/a"
in the checkbox -->
- [ ] PR title respects [Conventional
Commits](https://www.conventionalcommits.org) (starts with `fix:`,
`feat:`, etc, and is suitable for user-facing release notes)
- [ ] PR contains no breaking changes, **OR** description of both PR
**and final merge commit** starts with `BREAKING CHANGE:`
- [ ] (if applicable) Addresses issue: #0000
- [ ] Added relevant unit tests for your changes
- [ ] Ran `yarn precheckin`
- [ ] Verified code coverage for the changes made

Author: JGibson2019

README.md

@@ -14,7 +14,7 @@ Convert [axe-core](https://github.com/dequelabs/axe-core) accessibility scan res
 
 Use this with the [Sarif Viewer Build Tab Azure DevOps Extension](https://marketplace.visualstudio.com/items?itemName=sariftools.sarif-viewer-build-tab) to visualize accessibility scan results in the build results of an [Azure Pipelines](https://azure.microsoft.com/en-us/services/devops/pipelines/) build.
 
-## Usage
+## USAGE
 
 Before using axe-sarif-converter, you will need to run an [axe](https://github.com/dequelabs/axe-core) accessibility scan to produce some axe results to convert. Typically, you would do this by using an axe integration library for your favorite browser automation tool ([@axe-core/puppeteer](https://github.com/dequelabs/axe-core-npm/tree/develop/packages/puppeteer), [@axe-core/webdriverjs](https://github.com/dequelabs/axe-core-npm/tree/develop/packages/webdriverjs), [cypress-axe](https://github.com/avanslaars/cypress-axe)).