updated docs for kproperties in columns selection dsl

Author: Jolanrensen

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/samples/api/Access.kt

@@ -707,8 +707,9 @@ class Access : TestBase() {
     }
 
     @Test
-    fun columnSelectors_kProperties() {
+    fun columnSelectors_kproperties() {
         // SampleStart
+        // by column name
         df.select { it[Person::name] }
         df.select { (Person::name)() }
         df.select { col(Person::name) }

docs/StardustDocs/topics/ColumnSelectors.md

@@ -55,6 +55,39 @@ df.select { name.all() }
 df.select { name.allDfs() }
 ```
 
+</tab>
+<tab title="Strings">
+
+```kotlin
+// by column name
+df.select { it["name"] }
+
+// by column path
+df.select { it["name"]["firstName"] }
+df.select { "name"["firstName"] }
+
+// with a new name
+df.select { "name" named "Full Name" }
+
+// converted
+df.select { "name"["firstName"]<String>().map { it.uppercase() } }
+
+// column arithmetics
+df.select { 2021 - "age"<Int>() }
+
+// two columns
+df.select { "name" and "age" }
+
+// by range of names
+df.select { "name".."age" }
+
+// all children of ColumnGroup
+df.select { "name".all() }
+
+// dfs traversal of all children columns
+df.select { "name".allDfs() }
+```
+
 </tab>
 <tab title="Accessors">
 
@@ -92,39 +125,42 @@ df.select { name.allDfs() }
 ```
 
 </tab>
-<tab title="Strings">
+<tab title="KProperties">
 
 ```kotlin
 // by column name
-df.select { it["name"] }
+df.select { it[Person::name] }
+df.select { (Person::name)() }
+df.select { col(Person::name) }
 
 // by column path
-df.select { it["name"]["firstName"] }
-df.select { "name"["firstName"] }
+df.select { it[Person::name][Name::firstName] }
+df.select { Person::name[Name::firstName] }
 
 // with a new name
-df.select { "name" named "Full Name" }
+df.select { Person::name named "Full Name" }
 
 // converted
-df.select { "name"["firstName"]<String>().map { it.uppercase() } }
+df.select { Person::name[Name::firstName].map { it.lowercase() } }
 
 // column arithmetics
-df.select { 2021 - "age"<Int>() }
+df.select { 2021 - (Person::age)() }
 
 // two columns
-df.select { "name" and "age" }
+df.select { Person::name and Person::age }
 
-// by range of names
-df.select { "name".."age" }
+// range of columns
+df.select { Person::name..Person::age }
 
 // all children of ColumnGroup
-df.select { "name".all() }
+df.select { Person::name.all() }
 
 // dfs traversal of all children columns
-df.select { "name".allDfs() }
+df.select { Person::name.allDfs() }
 ```
 
-</tab></tabs>
+</tab>
+</tabs>
 <!---END-->
 
 **Select columns by column index:**