add description to explain Drive Prefix

[bobafetthotmail]

added a description so people know how to configure Drive Prefix setting for their printer.

I moved the Print/Delete buttons to the left because after I added the description row they were moved too much to the right. I could not figure out a better way to fix the alignment issue.

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[bobafetthotmail]

Now it should be ok, I edited the label text and I used anchors.fill: parent to fix the anchor issue.

Since to fix this I had to open the file on my PC, the text editor program I use auto-deleted the "space bar characters" at the empty line 238 too.

[Jeredian]

closes #371