Documentation breakage

When preparing a new Debian package of 8.0.240, I noticed that some
documentation disappeared, apparently due to the following. The error
in Nettle.Sign is already corrected but not the others, AFAICT, and
I'm guessing that @exp should be @expr. Patch below, which I home
someone can apply right away.

ERROR: <Invalid error container: Tools.AutoDoc.AutoDocError(SourcePosition(File: /build/pike8.0-8.0.240/src/modules/Gmp/mpz_glue.c, lines: 668..668), "DocParser", "@exp cannot be used like this: @exp{ ... @}")>

ERROR: <Invalid error container: Tools.AutoDoc.AutoDocError(SourcePosition(File: /build/pike8.0-8.0.240/lib/modules/__builtin.pmod/Nettle.pmod/Sign.pike, lines: 102..102), "DocParser", "@item is not allowed inside @array (allowed children are: @elem)")>

ERROR: <Invalid error container: Tools.AutoDoc.AutoDocError(SourcePosition(File: /build/pike8.0-8.0.240/lib/modules/Crypto.pmod/ECC.pmod, lines: 286..286), "DocParser", "@item is not allowed inside @array (allowed children are: @elem)")>

ERROR: <Invalid error container: Tools.AutoDoc.AutoDocError(SourcePosition(File: /build/pike8.0-8.0.240/lib/modules/Crypto.pmod/RSA.pmod, lines: 368..368), "DocParser", "@item is not allowed inside @array (allowed children are: @elem)")>