Revert "Merge pull request #1381 from xzfc/master"

This reverts commit 6c0a596dacd7672e650847f1ed15e6a2a67b1483, reversing
changes made to 33d3a7c83b2f1d2cda22b53bf82d68267154cdfd.
CMake: Fix helptags generation.
Merge pull request #1387 from fwalch/fix-installation

Fix installation.
runtime/docs/msgpack-rpc: Misc. fixes

- Correct apostrophe usage, primarily with it's/its
- Correct usage of 'e.g.'
- Capitalize acronyms
- Prepend NVIM_LISTEN_ADDRESS with '$' to match previous instance
- Avoid awkward phrasing
- Make lists with an explicitly stated number of points numbered to
  match other such lists
- Added space before parentheses
- rm trailing whitespace
Merge pull request #1377 from Pyrohh/msgpack_rpc-doc-fixes

Misc. msgpack-rpc doc fixes