[docs][syscalls] Add TODOs about documenting system call rights

ZX-2399 #comment

Test: no functional change
Change-Id: I1f285c677e2444fcf1d720d7ecbd9f490c303962

[syscalls] Update parameter types and names

This CL updates the parameter types and names for a number of syscalls
to match the Zircon System API rubric. There's more work to do to make
all the syscalls conform to the rubric, but this change is a start.

Change-Id: I218ac5e7e0cbd80a8c69fef7891ad40b78b6b407

[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 4/n

This reverts commit d7c91f0a8a876bd4de8808595cafcd4f2c3fd7a1.

Change-Id: I5c61410f62850583a970d3ff2f44b6d58901509a

[revert] Revert "[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 4/n"

This reverts commit 2d25909b7ab244d73172c9f5bc11d85b49ccefbb.

Change-Id: I09efe4e1d69d7aeadb051936d3ddc8237e7d39cf

[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 4/n

Remove actual from zx_vmo_{read,write}
Mark zx_vmo_{read,write}_old as deprecated
Retarget most uses of zx_vmo_{read,write}_old to zx_vmo_{read,write}.

Still need to migrate a handful of uses of _old that had meaningful
usage of actual.
This is good enough to go ahead and migrate uses in Garnet and Topaz.

ZX-1802

Change-Id: If57329f9c5183a0dacd29083decbaf771925145f

[kernel][vmo][cached] Allow setting cache policy on regular paged VMOs

Only works for plain vmos, and then only if they're not cloned, mapped,
or committed in any way.

Currently sets the cache parameters for all mappings, but will work
towards requiring the caller match the cache policy.

ZX-1213 #progress

Change-Id: Ie3e30f66048a844e48385b628373121f8bd18d44

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[docs][errors] Rename all the errors in docs/ to MX_OK and MX_ERR_*

Change-Id: I62451456a83145760c6454a619d4c699ce8e9017

[kernel][vm][clone] implement VMO clone operation

Add a syscall and mechanism to create a clone of a range
of an existing vmo into a new vmo. At the moment only
supports the COPY_ON_WRITE flag, so the cloned vmo will
fault in new copies of pages as they are written to.

Change-Id: I318182438a411952fdcf1cc121f59b600587c852

[docs][syscalls] Fix all the manpages

Change-Id: Ie9ba25060f3331de8d9c178caf6332fb48fc80f5

Remove mx_size_t and mx_ssize_t types

mx_ssize_t is no longer used. mx_size_t is superfluous and
can be replaced by the standard C type size_t.

Change-Id: I2137af6f166099d2e8aaca4fab63ff101f2a43ac

[docs][syscalls][vmo] start some simple syscall docs for vmos

Change-Id: I428d83224d977e83d8e3a543984a903d2615c0a1