FP Growth Documentation

[nikitajangid33]

I would like to add FP Growth algorithm documentation.
I am a GSSOC'21 participant

[geekquad]

Go ahead @nikitajangid33.

[Manasi2001]

Can I work on this @geekquad @yukti845? There's been no work done towards making a PR for this issue. Kindly assign it to me.

[yukti845]

@nikitajangid33 we need updates on this issue.

[yukti845]

@Manasi2001 go with this issue