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Add documentation for qualified operators and type operators (#462)

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- Syntax.md

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`‎language/Syntax.md`

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Original file line number	Diff line number	Diff line change
`@@ -375,15 +375,32 @@ fourToSix = Cons 4 (Cons 5 (Cons 6 Nil))`
`375`	`375`	`oneToSix = oneToThree <> fourToSix`
`376`	`376`	```
`377`	`377`
`378`		`-Operator alias declarations are made up of four parts:`
	`378`	+Types can also serve as operators. Consider this example from the module `Data.Tuple.Nested` of `purescript-tuples`:
	`379`	+```purescript
	`380`	`+infixr 6 type Tuple as /\`
	`381`	+```
	`382`	`+`
	`383`	`+Operator alias declarations are made up of five parts:`
`379`	`384`
`380`	`385`	* The associativity: either `infixl`, `infixr`, or `infix`.
`381`	`386`	`* The precedence: an integer, between 0 and 9. Here, it is 5.`
	`387`	+* The `type` keyword, if the symbol to be aliased is a type constructor.
`382`	`388`	* The function to alias: here, `append`
`383`	`389`	* The operator: here, `<>`.
`384`	`390`
`385`	`391`	`The declaration determines how expressions involving this operator are bracketed.`
`386`	`392`
	`393`	`+### Qualified operators`
	`394`	`+`
	`395`	`+Operators can be imported from other modules in their qualified form. For example:`
	`396`	`+`
	`397`	+```purescript
	`398`	`+import Data.Tuple as Tuple`
	`399`	`+`
	`400`	`+tuple :: Int Tuple./\ Int Tuple./\ Int`
	`401`	`+tuple = 1 Tuple./\ 2 Tuple./\ 3`
	`402`	+```
	`403`	`+`
`387`	`404`	`### Associativity`
`388`	`405`
`389`	`406`	`infixl` means that repeated applications are bracketed starting from the left. For example, `#` from Prelude is left-associative, meaning that an expression such as:
`@@ -476,6 +493,11 @@ Operators can be used as normal values by surrounding them with parentheses:`
`476`	`493`	`and = (&&)`
`477`	`494`	```
`478`	`495`
	`496`	`+For qualified operators, enclosing parentheses come after the qualifying module:`
	`497`	+```purescript
	`498`	`+and = Data.HeytingAlgebra.(&&)`
	`499`	+```
	`500`	`+`
`479`	`501`	`### Operator sections`
`480`	`502`
`481`	`503`	Operators can be partially applied by surrounding them with parentheses and using `_` as one of the operands:

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