Fix typo in documentation

[KenjiOhtsuka]

Fixed misspelling.

/dics/src/changes_080.rst contains the word "mmapped". Is it the misspelling of "mapped"? If so, I'll fix it too.

Large matrices (numpy/scipy.sparse, in LsiModel, Similarity etc.) are now mmapped to/from disk when doing save/load. The cPickle approach used previously was too buggy <http://groups.google.com/group/gensim/browse_thread/thread/3c4c6c0f76c5938c#>_ and slow <http://dieter.plaetinck.be/poor_mans_pickle_implementations_benchmark.html>_.

[piskvorky]

Thanks for the typo fix.

mmap is not a misspelling, but if you see it used somewhere prominent, feel free to hyperlink the term to https://en.wikipedia.org/wiki/Mmap (in case it helps others).

[menshikh-iv]

Thanks @KenjiOhtsuka, congratz with first contribution 🥇

[piskvorky]

Eh, changing the release notes of Gensim 0.8.0 (> 7 years ago) was not really necessary :)

I meant hyperlinking mmap in actual documentation -- where it matters, where people can see it.