chore: propagate format migration to README examples

Extends 8adce00 to the matching README example blocks. Athan Reines flagged that the `examples/index.js` fix needed to land in the READMEs too; updates `utils/async/inmap`, `utils/async/inmap-right`, `utils/async/for-each`, and `datasets/us-states-capitals-names` README examples to use `@stdlib/string/format` instead of string concatenation inside `new Error(...)`.

Author: claude

lib/node_modules/@stdlib/datasets/us-states-capitals-names/README.md

@@ -104,6 +104,7 @@ var t = table();
 
 ```javascript
 var capitalize = require( '@stdlib/string/capitalize' );
+var format = require( '@stdlib/string/format' );
 var table = require( '@stdlib/datasets/us-states-capitals-names' );
 
 var tbl = table();
@@ -123,7 +124,7 @@ function getState( capital ) {
 
     // Ensure a valid capital name was provided...
     if ( state === void 0 ) {
-        throw new Error( 'unrecognized capital. Value: `' + capital + '`.' );
+        throw new Error( format( 'unrecognized capital. Value: `%s`.', capital ) );
     }
     return state;
 }

lib/node_modules/@stdlib/utils/async/for-each/README.md

@@ -280,6 +280,7 @@ The function accepts the same `options` as `forEachAsync()`.
 ```javascript
 var resolve = require( 'path' ).resolve;
 var readFile = require( '@stdlib/fs/read-file' );
+var format = require( '@stdlib/string/format' );
 var forEachAsync = require( '@stdlib/utils/async/for-each' );
 
 var files = [
@@ -302,7 +303,7 @@ function read( file, next ) {
 
     function onFile( error ) {
         if ( error ) {
-            error = new Error( 'unable to read file: '+file );
+            error = new Error( format( 'unable to read file: %s', file ) );
             return next( error );
         }
         console.log( 'Successfully read file: %s', file );

lib/node_modules/@stdlib/utils/async/inmap-right/README.md

@@ -366,6 +366,7 @@ The function accepts the same `options` as `inmapRightAsync()`.
 ```javascript
 var resolve = require( 'path' ).resolve;
 var readFile = require( '@stdlib/fs/read-file' );
+var format = require( '@stdlib/string/format' );
 var inmapRightAsync = require( '@stdlib/utils/async/inmap-right' );
 
 var files = [
@@ -388,7 +389,7 @@ function read( file, next ) {
 
     function onFile( error, data ) {
         if ( error ) {
-            error = new Error( 'unable to read file: '+file );
+            error = new Error( format( 'unable to read file: %s', file ) );
             return next( error );
         }
         next( null, data );

lib/node_modules/@stdlib/utils/async/inmap/README.md

@@ -367,6 +367,7 @@ The function accepts the same `options` as `inmapAsync()`.
 ```javascript
 var resolve = require( 'path' ).resolve;
 var readFile = require( '@stdlib/fs/read-file' );
+var format = require( '@stdlib/string/format' );
 var inmapAsync = require( '@stdlib/utils/async/inmap' );
 
 var files = [
@@ -389,7 +390,7 @@ function read( file, next ) {
 
     function onFile( error, data ) {
         if ( error ) {
-            error = new Error( 'unable to read file: '+file );
+            error = new Error( format( 'unable to read file: %s', file ) );
             return next( error );
         }
         next( null, data );