[Bug] Fix mustache template

[sserrata]

Description

Fixes broken conditional statement in docusaurus-plugin-openapi default mustache template that prevented api frontmatter from getting written to MDX files.

Motivation and Context

Issue prevents ApiDemoPanel from displaying.

How Has This Been Tested?

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes if appropriate.
• All new and existing tests passed.

[github-actions]

Size Change: +9 B (0%)

Total Size: 2.36 MB

ℹ️ View Unchanged

Filename	Size	Change
demo/.docusaurus/globalData.json	8.72 kB	0 B
demo/build/assets/css/styles.********.css	85 kB	0 B
demo/build/assets/js/066d920b.********.js	6.82 kB	0 B
demo/build/assets/js/0de0d9d3.********.js	11.4 kB	0 B
demo/build/assets/js/0e384e19.********.js	2.39 kB	0 B
demo/build/assets/js/0f5373df.********.js	9.78 kB	0 B
demo/build/assets/js/11cd04f0.********.js	15.8 kB	0 B
demo/build/assets/js/17896441.********.js	1.55 kB	0 B
demo/build/assets/js/18927b64.********.js	20 kB	0 B
demo/build/assets/js/18c41134.********.js	14.7 kB	0 B
demo/build/assets/js/1be78505.********.js	10.8 kB	0 B
demo/build/assets/js/1e4232ab.********.js	3.45 kB	0 B
demo/build/assets/js/1f391b9e.********.js	2.6 kB	0 B
demo/build/assets/js/1f41b3da.********.js	11.2 kB	0 B
demo/build/assets/js/2695.********.js	1.02 kB	0 B
demo/build/assets/js/2c9e856c.********.js	11.7 kB	0 B
demo/build/assets/js/3372.********.js	11.5 kB	0 B
demo/build/assets/js/393be207.********.js	921 B	0 B
demo/build/assets/js/42c7b392.********.js	17.8 kB	0 B
demo/build/assets/js/4685.********.js	1.1 MB	0 B
demo/build/assets/js/46a8ec8c.********.js	20.4 kB	0 B
demo/build/assets/js/477c195c.********.js	4.71 kB	0 B
demo/build/assets/js/4a47cb6d.********.js	1.34 kB	0 B
demo/build/assets/js/4c5e977b.********.js	36.9 kB	0 B
demo/build/assets/js/4c9d5d90.********.js	19.5 kB	0 B
demo/build/assets/js/4e8c00d7.********.js	9.79 kB	0 B
demo/build/assets/js/533a09ca.********.js	2.8 kB	0 B
demo/build/assets/js/5456.********.js	10 kB	0 B
demo/build/assets/js/5c2e4ff8.********.js	17 kB	0 B
demo/build/assets/js/5c868d36.********.js	3.52 kB	0 B
demo/build/assets/js/6ab70d68.********.js	10.2 kB	0 B
demo/build/assets/js/6d9cbd66.********.js	20.6 kB	0 B
demo/build/assets/js/71d92ba4.********.js	4.32 kB	0 B
demo/build/assets/js/7608cde2.********.js	1.31 kB	+3 B (0%)
demo/build/assets/js/8084356f.********.js	10.9 kB	0 B
demo/build/assets/js/822bd8ab.********.js	3.19 kB	0 B
demo/build/assets/js/846aa161.********.js	17.6 kB	0 B
demo/build/assets/js/888b62d9.********.js	1.49 kB	+3 B (0%)
demo/build/assets/js/8dd270d8.********.js	29.4 kB	0 B
demo/build/assets/js/935f2afb.********.js	3.54 kB	0 B
demo/build/assets/js/9719473f.********.js	1.24 kB	+3 B (0%)
demo/build/assets/js/9e4087bc.********.js	1.61 kB	0 B
demo/build/assets/js/a9d8a64b.********.js	2.44 kB	0 B
demo/build/assets/js/b0e6d8b9.********.js	2.32 kB	0 B
demo/build/assets/js/b2f554cd.********.js	121 B	0 B
demo/build/assets/js/bb0d0959.********.js	2.12 kB	0 B
demo/build/assets/js/bd766368.********.js	9.49 kB	0 B
demo/build/assets/js/c3d13055.********.js	8.63 kB	0 B
demo/build/assets/js/c4f5d8e4.********.js	72.3 kB	0 B
demo/build/assets/js/ce11f325.********.js	10.9 kB	0 B
demo/build/assets/js/common.********.js	125 kB	0 B
demo/build/assets/js/d03381af.********.js	22.2 kB	0 B
demo/build/assets/js/da717792.********.js	16.4 kB	0 B
demo/build/assets/js/dc10a35a.********.js	16.5 kB	0 B
demo/build/assets/js/dde745ce.********.js	15.2 kB	0 B
demo/build/assets/js/dff1c289.********.js	4.2 kB	0 B
demo/build/assets/js/e1362e6d.********.js	1.37 kB	0 B
demo/build/assets/js/e44a2883.********.js	5.45 kB	0 B
demo/build/assets/js/f55d3e7a.********.js	3.01 kB	0 B
demo/build/assets/js/main.********.js	390 kB	0 B
demo/build/assets/js/runtime~main.********.js	6.35 kB	0 B
demo/build/index.html	72.6 kB	0 B

_{compressed-size-action}

[github-actions]

Visit the preview URL for this PR (updated for commit c1f8844):

https://docusaurus-openapi-36b86--pr49-o8gtqumk.web.app

_{(expires Sat, 14 May 2022 13:08:25 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}