bug#22889: small fixes to guile manual

[Ethan Stefan Day]

I fixed a few small problems I found in the Guile manual as I was
reading it.  I edited against the version I found here
https://www.gnu.org/software/guile/manual/guile.texi.tar.gz
at about 7pm EST on March 2, 2016.  Most of the fixes are very small,
but the thing with car in api-data.texi could really confuse someone
learning scheme as one of their first programming languages.

-Ethan Day

api-compound.texi.diff
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api-control.texi.diff
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api-data.texi.diff
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