Auto merge of #19097 - marmistrz:doc-python34, r=emilio

Mention that we need Python3 to build on CentOS

Mention that we need Python3 to build on CentOS

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- [x] `./mach test-tidy` does not report any errors

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- [ ] There are tests for these changes OR
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README.md

@@ -74,6 +74,16 @@ sudo dnf install curl freeglut-devel libtool gcc-c++ libXi-devel \
     rpm-build openssl-devel cmake bzip2-devel libXcursor-devel libXmu-devel mesa-libOSMesa-devel \
     dbus-devel ncurses-devel
 ```
+#### On CentOS
+
+``` sh
+sudo yum install curl freeglut-devel libtool gcc-c++ libXi-devel \
+    freetype-devel mesa-libGL-devel mesa-libEGL-devel glib2-devel libX11-devel libXrandr-devel gperf \
+    fontconfig-devel cabextract ttmkfdir python python-virtualenv python-pip expat-devel \
+    rpm-build openssl-devel cmake bzip2-devel libXcursor-devel libXmu-devel mesa-libOSMesa-devel \
+    dbus-devel ncurses-devel python34
+```
+
 #### On openSUSE Linux
 ``` sh
 sudo zypper install libX11-devel libexpat-devel libbz2-devel Mesa-libEGL-devel Mesa-libGL-devel cabextract cmake \