added the drone security cheatsheet

[pUrGe12]

Created the drone security cheat sheet. Kindly review and suggest changes.

Please make sure that for your contribution:

• In case of a new Cheat Sheet, you have used the Cheat Sheet template.
• All the markdown files do not raise any validation policy violation, see the policy.
• All the markdown files follow these format rules.
• All your assets are stored in the assets folder.
• All the images used are in the PNG format.
• Any references to websites have been formatted as [TEXT](URL)
• You verified/tested the effectiveness of your contribution (e.g., the defensive code proposed is really an effective remediation? Please verify it works!).
• The CI build of your PR pass, see the build status here.

If your PR is related to an issue, please finish your PR text with the following line:

This PR fixes issue #1412.

[jmanico]

Some lint errors:

cheatsheets/Drone_security_sheet.md:25 MD022/blanks-around-headings/blanks-around-headers Headings should be surrounded by blank lines [Expected: 1; Actual: 0; Below] [Context: "### 1. Communication Security"]
cheatsheets/Drone_security_sheet.md:26 MD032/blanks-around-lists Lists should be surrounded by blank lines [Context: "- **Insecure Communication Lin..."]
cheatsheets/Drone_security_sheet.md:29:1 MD007/ul-indent Unordered list indentation [Expected: 4; Actual: 2]
cheatsheets/Drone_security_sheet.md:33:48 MD009/no-trailing-spaces Trailing spaces [Expected: 0 or 2; Actual: 1]
cheatsheets/Drone_security_sheet.md:64:225 MD009/no-trailing-spaces Trailing spaces [Expected: 0 or 2; Actual: 1]
cheatsheets/Drone_security_sheet.md:80:90 MD009/no-trailing-spaces Trailing spaces [Expected: 0 or 2; Actual: 1]
cheatsheets/Drone_security_sheet.md:88:221 MD009/no-trailing-spaces Trailing spaces [Expected: 0 or 2; Actual: 1]
cheatsheets/Drone_security_sheet.md:104:269 MD009/no-trailing-spaces Trailing spaces [Expected: 0 or 2; Actual: 1]
cheatsheets/Drone_security_sheet.md:117:80 MD047/single-trailing-newline Files should end with a single newline character

[pUrGe12]

I will fix them now.

[pUrGe12]

Hello, any updates on this? Should I change anything in the sheet?