[COMMITTED 14/19] gccrs: install.texi: Mention Rust requirement for building gccrs

[arthur.cohen@embecosm.com]

From: Arthur Cohen <arthur.cohen@embecosm.com>

Addresses PR#117869

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117869

gcc/ChangeLog:

	* doc/install.texi: Add requirements for building gccrs.
---
 gcc/doc/install.texi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index b5509ff0c86..1af0082ed77 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -350,6 +350,12 @@ documentation including the target @code{SYSTEM} definition module.
 If Python3 is unavailable Modula-2 documentation will include a target
 independent version of the SYSTEM modules.
 
+@item @anchor{gccrs-prerequisite}gccrs
+
+The official Rust compiler and Rust build system (cargo) are required for
+building various parts of the gccrs frontend, until gccrs can compile them
+by itself. The minimum supported Rust version is 1.49.
+
 @item A ``working'' POSIX compatible shell, or GNU bash
 
 Necessary when running @command{configure} because some
-- 
2.49.0