Markdown component doesn't handle relative urls, only absolute

[JulieMarie]

Describe the bug
When creating url for svg images in the markdown component, only absolute paths work, relative path do not. For using IPH files offline, the component needs to handle relative paths as well as absolute paths.

To Reproduce
Steps to reproduce the behavior:

1. Change IPH to host file for offline use
2. Try to open a md file that calls out an image
3. Note the error in the console

Expected behavior
User expects to see help files displayed properly whether they are online or offline

Screenshots
md file without image that works:

md file with image that doesn't work:

Desktop (please complete the following information):

• OS: macOS
• Browser No browser, running Electron app
• Version N/A

Additional context
N/A