ICU-22922 update collation demo list of tailorings (#47)

Author: sven-oly

webdemo/collation/index.html

@@ -126,6 +126,7 @@ <h1><a href="https://icu.unicode.org/">ICU</a> Collation Demo</h1>
 <option value="ne">ne (type=standard):   Nepali (Standard Sort Order)</option>
 <option value="no">no (type=standard):   Norwegian (Standard Sort Order)</option>
 <option value="no@collation=search">no-u-co-search (normalization=on):   Norwegian (General-Purpose Search)</option>
+<option value="nso">nso (type=standard):   Northern Sotho (Standard Sort Order)</option>
 <option value="om">om (type=standard):   Oromo (Standard Sort Order)</option>
 <option value="or">or (type=standard, normalization=on):   Odia (Standard Sort Order)</option>
 <option value="pa">pa (type=standard, normalization=on):   Punjabi (Standard Sort Order)</option>
@@ -153,6 +154,7 @@ <h1><a href="https://icu.unicode.org/">ICU</a> Collation Demo</h1>
 <option value="te">te (type=standard, normalization=on):   Telugu (Standard Sort Order)</option>
 <option value="th">th (type=standard, alternate=shifted, normalization=on):   Thai (Standard Sort Order)</option>
 <option value="tk">tk (type=standard):   Turkmen (Standard Sort Order)</option>
+<option value="tn">tn (type=standard):   Tswana (Standard Sort Order)</option>
 <option value="to">to (type=standard):   Tongan (Standard Sort Order)</option>
 <option value="tr">tr (type=standard):   Turkish (Standard Sort Order)</option>
 <option value="tr@collation=search">tr-u-co-search (normalization=on):   Turkish (General-Purpose Search)</option>