add explanations of any and all.equal

[chadyuu]

There are no explanations of any and all.equal even though they are referred to here. https://github.com/daviddalpiaz/appliedstats/blob/53b7a49e71120ddb86aab23290ab5cbd2c1919f8/data-and-programming.Rmd#L268-L271

So I added some explanations.

Although we have an brief explanation of all.equal later, I feel like the new explanation would be helpful. https://github.com/daviddalpiaz/appliedstats/blob/53b7a49e71120ddb86aab23290ab5cbd2c1919f8/data-and-programming.Rmd#L371

Any feedback would be much appreciated.

[daviddalpiaz]

Generally good! A few suggestions:

• I think I'd replace "their" with "its" every time it appears, although I could be convinced otherwise, but "its" sounds more correct to me.
• I'd maybe add a line right before line 276 with just x == y so that it's super obvious that the vector that is returned by that is what any and all are operating on.
• To avoid starting a sentence with a function name (and thus not starting with a capital letter) consider using "The all.equal function..." as a workaround. (Credit to Unger for teaching me this trick.)

[chadyuu]

@daviddalpiaz Thanks! I updated the content, following your advice. Please recheck it.

[daviddalpiaz]

Thanks again!