Describe new compression method API in documentation

[cary-ilm]

Add to https://openexr.com/en/latest/ReadingAndWritingImageFiles.html#compression, source is here.

In anticipation of future support for new compression types, there is now a convenience API for mapping between compression type names and the associated enum:

getCompressionDescriptionFromId(Compression, std::string&)
getCompressionIdFromName(const std::string&, Compression&)
getCompressionNameFromId(Compression, std::string&)
getCompressionNamesString(const std::string&, std::string&)
getCompressionNumScanlines(Compression)
isValidCompression(int)

[SaxenaAnushka102]

Hello @cary-ilm! I'd like to take this up. The source link is showing "Not found". Could you please help with the active link? Thanks!

[cary-ilm]

@SaxenaAnushka102, thanks! The link to the source is fixed now. Hopefully reading the source code and comment will explain what each function does.