simd.7: add scalar strchrnul() for RISC-V to manpage

index() and strchr() are implemented by calling strchrnul(), so they
also get to be marked as platform-specific.

MFC after:	1 month
MFC to:		stable/15
Approved by:	markj (mentor)
Reviewed by:	fuz
Sponsored by:	Google LLC (GSoC 2024)
Differential Revision:	https://reviews.freebsd.org/D46047

share/man/man7/simd.7

@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE
 .
-.Dd October 16, 2025
+.Dd October 21, 2025
 .Dt SIMD 7
 .Os
 .Sh NAME
@@ -55,7 +55,7 @@ Enhanced functions are present for the following architectures:
 .It    bcopy             Ta    A       Ta    S   Ta    S      Ta    S    Ta    SV
 .It    bzero             Ta    A       Ta    S   Ta    S      Ta    S
 .It    div               Ta            Ta        Ta    S      Ta    S
-.It    index             Ta    A       Ta        Ta    S1
+.It    index             Ta    A       Ta        Ta    S1                Ta          Ta    S
 .It    ldiv              Ta            Ta        Ta    S      Ta    S
 .It    lldiv             Ta            Ta        Ta    S
 .It    memchr            Ta    A       Ta        Ta    S1     Ta         Ta          Ta    S
@@ -69,8 +69,8 @@ Enhanced functions are present for the following architectures:
 .It    stpcpy            Ta    A       Ta        Ta    S1
 .It    stpncpy           Ta            Ta        Ta    S1
 .It    strcat            Ta    A       Ta        Ta    S1     Ta    S
-.It    strchr            Ta    A       Ta        Ta    S1     Ta    S
-.It    strchrnul         Ta    A       Ta        Ta    S1
+.It    strchr            Ta    A       Ta        Ta    S1     Ta    S    Ta          Ta    S
+.It    strchrnul         Ta    A       Ta        Ta    S1     Ta         Ta          Ta    S
 .It    strcmp            Ta    A       Ta    S   Ta    S1     Ta    S
 .It    strcpy            Ta    A       Ta        Ta    S1     Ta    S    Ta    S2
 .It    strcspn           Ta    S       Ta        Ta    S2