Flex is not a GNU package

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/10/static/install-requirements.html
Description:

On the page

https://www.postgresql.org/docs/10/static/install-requirements.html

the line

"GNU Flex and Bison are needed to build from a Git checkout..."

should be changed to

"Flex and Bison are needed to build from a Git checkout..."

The reason is because Flex is not a GNU package; it is BSD-licensed and
copyrighted by the University of California. Bison does not need to be
explicitly identified as GNU Bison, because there is only one Bison and it
is widely known as the GNU implementation of yacc.

---

diff --git a/doc/src/sgml/installation.sgml
b/doc/src/sgml/installation.sgml
index a922819..141494c 100644
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -289,7 +289,7 @@ su - postgres
<primary>yacc</primary>
</indexterm>

- GNU <application>Flex</application> and
<application>Bison</application>
+ <application>Flex</application> and
<application>Bison</application>
are needed to build from a Git checkout, or if you changed the
actual
scanner and parser definition files. If you need them, be sure
to get <application>Flex</application> 2.5.31 or later and