sra/doc: Document param sra-max-propagations

I forgot to document the new param in invoke.texi, does the text below
look OK?

Tested with make info and make pdf.

Thanks,

Martin

2020-04-02  Martin Jambor  <mjambor@suse.cz>

	* doc/invoke.texi (Optimize Options): Document sra-max-propagations.

gcc/ChangeLog

+2020-04-02  Martin Jambor  <mjambor@suse.cz>
+
+	* doc/invoke.texi (Optimize Options): Document sra-max-propagations.
+
 2020-04-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/92264

gcc/doc/invoke.texi

@@ -12785,6 +12785,11 @@ speed
 (@option{sra-max-scalarization-size-Ospeed}) or size
 (@option{sra-max-scalarization-size-Osize}) respectively.
 
+@item sra-max-propagations
+The maximum number of artificial accesses that Scalar Replacement of
+Aggregates (SRA) will track, per one local variable, in order to
+facilitate copy propagation.
+
 @item tm-max-aggregate-size
 When making copies of thread-local variables in a transaction, this
 parameter specifies the size in bytes after which variables are