Fix strapi-provider-upload-local readme

[remidej]

Description of what you did:

Fixed the Readme docs of the strapi-provider-upload-local package.

They talked about Cloudinary, probably because of a copy and paste mistake.

I also wrote that the sizeLimit config value should be specified in bytes and not KB, since it seems to rely on File.size

[codecov]

Codecov Report

Merging #7373 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #7373   +/-   ##
=======================================
  Coverage   26.22%   26.22%           
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  Files        1131     1131           
  Lines       15433    15433           
  Branches     2443     2443           
=======================================
  Hits         4048     4048           
  Misses       9565     9565           
  Partials     1820     1820           

Flag	Coverage Δ
#front	18.26% <ø> (ø)
#unit	53.14% <ø> (ø)

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[alexandrebodin]

LGTM