### Conflict-free release note entries for GitHub pull requests

GitHub [PR #628](https://github.com/epics-base/epics-base/pull/628)

This release replaces the developer-edited `documentation/RELEASE_NOTES.md`
source file in the EPICS tree with a process which generates that file from a
series of individual files added for each changeset in the release, thus
preventing merge conflicts when entries are added by many different pull
requests.

For this new approach each pull request must add its own Markdown file to the
`documentation/new-notes` directory, using a unique filename.
When a release is made, all these files will be combined into a single
`RELEASE-<version>.md` file and the `new-notes` directory emptied to prepare
for development of the next release.

Developers can generate the `RELEASE_NOTES.md` file by running `make` in the
`documentation` directory, which will install the result in the `doc` top-level
directory along with the `RELEASE-<version>.md` files describing older EPICS
releases going back to 3.15.
The `documentation/Makefile` provides some other targets which can also be
requested, but they require additional non-EPICS software such as Doxygen and
Sphinx to have been installed first.

Between releases the generated `RELEASE_NOTES.md` file contains the text from
any `new-notes` files added to document changes already merged.
It also provides links to the older `RELEASE-<version>.md` files, so it remains
the starting point for documentation on all release changes.

Detailed instructions on creating new entries are provided in a `README.txt`
file in the `documentation/new-notes` directory.
The release-time process that generates a new `RELEASE-<version>.md` file is
described in the `documentation/ReleaseChecklist.html` file.