v0.21.5

DataFrames v0.21.5

Diff since v0.21.4

Closed issues:

• How to save dataframe to CSV file (#2312)
• Single row manipulation leads to wrong results (#2332)

Merged pull requests:

• Up Documenter.jl (#2315) (@bkamins)
• fix deprecated example in the docs for innerjoin (#2320) (@bkamins)
• fix DataFrameRow setindex! (#2333) (@bkamins)