Documentation update re: DAP2 protocol reserved keywords

[WardF]

The following was sent out by @DennisHeimbigner to the thredds community; it contains information that needs to be propagated into the netCDF-C documentation.

---

I have been asked to share this information with the
thredds community.

In the OPeNDAP DAP2 protocol, there are a number of
keywords. These keywords are case insensitive and if
you use one of them as your variable names, you may
encounter odd behavior such as case changes
(depending on the client DDS/DAS parser)

Anyway, below is the list of reserved keywords as used by the
netcdf-C library parser.
=Dennis Heimbigner
Unidata

"alias",
"array",
"attributes",
"byte",
"dataset",
"error",
"float32",
"float64",
"grid",
"int16",
"int32",
"maps",
"sequence",
"string",
"structure",
"uint16",
"uint32",
"url",
"code",
"message",
"program_type",
"program",

[WardF]

Documentation updated in branch gh308; when travis checks end, I will merge over.

[WardF]

Fixed, merged.