Mobile Burundi validation

[pavolmarc]

Added Burundi phone validation, also edited readme file.

Checklist

• [X] PR contains only changes related; no stray files, etc.
• [X] README updated (where applicable)
• [x] Tests written (where applicable)

[codecov[bot]]

Codecov Report

Merging #1872 (91f0ed3) into master (f055c11) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1872   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          102       102           
  Lines         2072      2072           
  Branches       472       472           
=========================================
  Hits          2072      2072           

Impacted Files	Coverage Δ
src/lib/isMobilePhone.js	100.00% <ø> (ø)

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[pavolmarc]

@tux-tn Thank you for good points, I added tests and mobile phone specification

[pavolmarc]

@tux-tn thank you, so whats the next step? Do i have to merge this or is it done by you or automaticaly?

[ezkemboi]

@pavolmarc, the one to merge for now is @profnandaa unless he gives @ezkemboi or @tux-tn a go-ahead.

[profnandaa]

@pavolmarc -- just confirming, should Burundi's locale be rn-BI not en-BI? https://www.localeplanet.com/icu/rn-BI/index.html

[profnandaa]

If anyone can help clean up this PR, will get it in.

[rubiin]

@profnandaa I can do that