Remove old mention of the fewerBraces

Author: Kordyjan

docs/_docs/reference/other-new-features/indentation.md

@@ -502,62 +502,3 @@ indented regions where possible. When invoked with options `-rewrite -no-indent`
 The `-indent` option only works on [new-style syntax](./control-syntax.md). So to go from old-style syntax to new-style indented code one has to invoke the compiler twice, first with options `-rewrite -new-syntax`, then again with options
 `-rewrite -indent`. To go in the opposite direction, from indented code to old-style syntax, it's `-rewrite -no-indent`, followed by `-rewrite -old-syntax`.
 
-### Variant: Indentation Marker `:` for Arguments
-
-Generally, the possible indentation regions coincide with those regions where braces `{...}` are also legal, no matter whether the braces enclose an expression or a set of definitions. There is one exception, though: Arguments to functions can be enclosed in braces but they cannot be simply indented instead. Making indentation always significant for function arguments would be too restrictive and fragile.
-
-To allow such arguments to be written without braces, a variant of the indentation scheme is implemented under language import
-```scala
-import language.experimental.fewerBraces
-```
-In this variant, a `<colon>` token is also recognized where function argument would be expected. Examples:
-
-```scala
-times(10):
-  println("ah")
-  println("ha")
-```
-
-or
-
-```scala
-credentials `++`:
-  val file = Path.userHome / ".credentials"
-  if file.exists
-  then Seq(Credentials(file))
-  else Seq()
-```
-
-or
-
-```scala
-xs.map:
-  x =>
-    val y = x - 1
-    y * y
-```
-What's more, a `:` in these settings can also be followed on the same line by the parameter part and arrow of a lambda. So the last example could be compressed to this:
-
-```scala
-xs.map: x =>
-  val y = x - 1
-  y * y
-```
-and the following would also be legal:
-```scala
-xs.foldLeft(0): (x, y) =>
-  x + y
-```
-
-The grammar changes for this variant are as follows.
-
-```
-SimpleExpr       ::=  ...
-                   |  SimpleExpr ColonArgument
-InfixExpr        ::=  ...
-                   |  InfixExpr id ColonArgument
-ColonArgument    ::=  colon [LambdaStart]
-                      indent (CaseClauses | Block) outdent
-LambdaStart      ::=  FunParams (‘=>’ | ‘?=>’)
-                   |  HkTypeParamClause ‘=>’
-```