[MISC] Fighting ping spam

[ppfeufer]

Description

Added

• Warning about ping spam when @everyone is selected as target. Hopefully this
  will fight ping spam a little.

Type of change

Please delete options that are not relevant.

• 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 not
  work as expected)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have checked my code and corrected any misspellings

[codecov]

Codecov Report

Merging #84 (f27b4bd) into master (fc56400) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master      #84   +/-   ##
=======================================
  Coverage   71.66%   71.66%           
=======================================
  Files          16       16           
  Lines         593      593           
  Branches       85       85           
=======================================
  Hits          425      425           
  Misses        147      147           
  Partials       21       21           

Impacted Files	Coverage Δ
fleetpings/__init__.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update fc56400...f27b4bd. Read the comment docs.