Release Notes: stop mentioning winpty

For a long time we used the MSYS2 runtime in a in a mode where it did
not use the Pseudo Consoles that are nowadays supported by Windows. For
that reason, when running in MinTTY, which is the default terminal of
Git Bash, we had to use aliases that ran interpreters like Python and
Ruby through WinPTY.

However, going with the times, we followed the MSYS2 project, which
switched to an MSYS2 runtime version that defaults to Pseudo Consoles
being supported and turned on. That makes these aliases to force WinPty
obsolete.

Git for Windows' release notes still talk about it though, in the "Known
Issues" section. Let's remove that item.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

ReleaseNotes.md

@@ -10,7 +10,6 @@ See [http://git-scm.com/](http://git-scm.com/) for further details about Git inc
 # Known issues
 * On Windows 10 before 1703, or when Developer Mode is turned off, special permissions are required when cloning repositories with symbolic links, therefore support for symbolic links is disabled by default. Use `git clone -c core.symlinks=true <URL>` to enable it, see details [here](https://gitforwindows.org/symbolic-links).
 * If configured to use Plink, you will have to connect with [putty](http://www.chiark.greenend.org.uk/~sgtatham/putty/) first and accept the host key.
-* Some console programs, most notably non-MSYS2 Python, PHP, Node and OpenSSL, interact correctly with MinTTY only when called through `winpty` (e.g. the Python console needs to be started as `winpty python` instead of just `python`).
 * If you specify command-line options starting with a slash, POSIX-to-Windows path conversion will kick in converting e.g. "`/usr/bin/bash.exe`" to "`C:\Program Files\Git\usr\bin\bash.exe`". When that is not desired -- e.g. "`--upload-pack=/opt/git/bin/git-upload-pack`" or "`-L/regex/`" -- you need to set the environment variable `MSYS_NO_PATHCONV` temporarily, like so:
 
   > `MSYS_NO_PATHCONV=1 git blame -L/pathconv/ msys2_path_conv.cc`