locate.1: clarify bytes vs. characters

The database stores bytes, not characters. Remove the historical
note about 7-bit storage. Also document that -i ignores case only
for ASCII letters.

Reviewed by: ziaee
MFC after: 3 days

usr.bin/locate/locate/locate.1

@@ -1,4 +1,4 @@
-.\" Copyright (c) 1995 Wolfram Schneider <[email protected]>. Berlin.
+.\" Copyright (c) 1995-2026 Wolfram Schneider <[email protected]>
 .\" Copyright (c) 1990, 1993
 .\"	The Regents of the University of California.  All rights reserved.
 .\"
@@ -26,7 +26,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd December 11, 2020
+.Dd October 22, 2026
 .Dt LOCATE 1
 .Os
 .Sh NAME
@@ -70,17 +70,16 @@ As a special case, a pattern containing no globbing characters
 is matched as though it were
 .Dq *foo* .
 .Pp
-Historically, locate only stored characters between 32 and 127.
-The
-current implementation stores any character except newline
+The database can store any byte in a path name except newline
 .Pq Sq \en
 and
 .Dv NUL
 .Pq Sq \e0 .
-The 8-bit character support does not waste extra space for
-plain ASCII file names.
-Characters less than 32 or greater than 127
-are stored in 2 bytes.
+Bytes with values from 32 to 127
+.Pq printable ASCII characters and DEL
+are stored in at most one byte;
+all other bytes take two bytes.
+For example, a two-byte UTF-8 character takes four bytes in the database.
 .Pp
 The following options are available:
 .Bl -tag -width 10n
@@ -159,6 +158,7 @@ Note: you can only use
 pattern for stdin.
 .It Fl i
 Ignore case distinctions in both the pattern and the database.
+Only ASCII letters are folded.
 .It Fl l Ar number
 Limit output to
 .Ar number
@@ -266,3 +266,6 @@ a locate database which was built on SunOS/sparc machine
 The
 .Nm
 utility does not recognize multibyte characters.
+The
+.Fl i
+option ignores case only for ASCII letters.