Update Vocabulary.rmd

Fixed a typo
typo
Missing hyperlink

Missing hyperlink to the chapter - this is not the only occurrence, there are more in this chapter alone.
Missing hyperlink

Missing hyperlink to chapter Environments. (will not report for further occurrences)
Missing hyperlink

Missing hyperlink; name of chapter abbreviated and therefore not clear. (Will not report for further occurrences.)
Missing full stops.
One dot too many

Four dots used instead of three.
Merge pull request #90 from crtahlin/patch-2

Missing hyperlink
Merge pull request #91 from crtahlin/patch-4

Missing hyperlink
Merge pull request #92 from crtahlin/patch-5

Missing hyperlink
Merge pull request #93 from crtahlin/patch-6

Missing full stops.
Merge pull request #95 from crtahlin/patch-9

One dot too many
Merge pull request #89 from fyears/patch-1

typo
Merge pull request #88 from thomasherbig/patch-1

Update Vocabulary.rmd
Polish intro. Add colophon
Missing full stop
Added full stops.

Added full stops and Caps at the start of senteces (seems to be the style used elsewhere). 

Also note - "etc." did not have a full stop as is the case in some other places in the text (candidate for search and replace).
More work on pros and cons
More intro polishing
Minor tweaks from reviewer