Change "point relase" to "patch release" for precision

In general, the software world is not clear about these terms. However,
the most common usage seems to use "point release" to refer to any
release with at least one period in the version number, which would also
include minor releases. By contrast, "patch release," though a much less
common phrase, unambiguously denotes a release with a version number
containing two periods.

See:
https://en.wikipedia.org/wiki/Point_release
https://semver.org/

user/downloading-installing-upgrading/supported-releases.md

@@ -29,13 +29,13 @@ are available from our [download mirrors](/downloads/#mirrors).
 | Release 4.0 | 2018-03-28 | TBA        | Supported             |
 | Release 4.1 | TBA        | TBA        | [In development](https://github.com/QubesOS/qubes-issues/issues?utf8=%E2%9C%93&q=is%3Aissue+milestone%3A%22Release+4.1%22+) |
 
-### Note on point releases
+### Note on patch releases
 
-Please note that point releases, such as 3.2.1 and 4.0.1, do not designate
+Please note that patch releases, such as 3.2.1 and 4.0.1, do not designate
 separate, new releases of Qubes OS. Rather, they designate their respective
 major or minor releases, such as 3.2 and 4.0, inclusive of all package updates
 up to a certain point. For example, installing Release 4.0 and fully updating
-it results in the same system as installing Release 4.0.1. Therefore, point
+it results in the same system as installing Release 4.0.1. Therefore, patch
 releases are not displayed as separate rows on any of the tables on this page.
 
 ## Dom0