Merge branch 'feature/LIGO-258-update-docs' into 'dev'

LIGO-258 Docs updates

Closes LIGO-258

See merge request ligolang/ligo!272

gitlab-pages/docs/advanced/entrypoints-contracts.md

@@ -220,7 +220,7 @@ In our case, we have a `counter.ligo` contract that accepts a parameter of type
 
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
-```pascaligo
+```pascaligo skip
 // counter.ligo
 type action is
 | Increment of int

gitlab-pages/docs/language-basics/boolean-if-else.md

@@ -139,21 +139,8 @@ Conditional logic is an important part of every real world program.
 ```pascaligo group=e
 const min_age: nat = 16n;
 
-(*
-    This function is really obnoxious, but it showcases
-    how the if statement and it's syntax can be used.
-
-    Normally, you'd use `with (age > min_age)` instead.
-*)
 function is_adult(const age: nat): bool is
-    block {
-        var is_adult: bool := False;
-        if (age > min_age) then begin
-            is_adult := True;
-        end else begin
-            is_adult := False;
-        end
-    } with is_adult
+    if (age > min_age) then True else False
 ```
 
 > You can run the function above with

gitlab-pages/docs/language-basics/math-numbers-tez.md

@@ -200,6 +200,18 @@ const a: int = int(1n);
 const b: nat = abs(1);
 ```
 
+<!--END_DOCUSAURUS_CODE_TABS-->
+
+## Check if a value is a `nat`
+
+You can check if a value is a `nat`, by using a syntax specific built-in function, which accepts an `int` and returns an `option(nat)`, more specifically `Some(nat)` if the provided integer is a natural number, and `None` otherwise:
+
+<!--DOCUSAURUS_CODE_TABS-->
+<!--Pascaligo-->
+```pascaligo
+const its_a_nat: option(nat) = is_nat(1)
+```
+
 <!--ReasonLIGO-->
 ```reasonligo group=e
 let a: int = int(1n);

gitlab-pages/docs/language-basics/src/boolean-if-else/if-else.ligo

@@ -0,0 +1,4 @@
+const min_age: nat = 16n;
+
+function is_adult(const age: nat): bool is
+    if (age > min_age) then True else False

gitlab-pages/docs/language-basics/src/math-numbers-tez/isnat.ligo

@@ -0,0 +1 @@
+const its_a_nat: option(nat) = is_nat(1)

gitlab-pages/docs/language-basics/src/types/annotation.ligo

@@ -0,0 +1,4 @@
+type int_map is map(int, int);
+function get_first(const int_map: int_map): option(int) is int_map[1]
+// empty map needs a type annotation
+const first: option(int) = get_first(((map end) : int_map ));

gitlab-pages/docs/language-basics/types.md

@@ -3,7 +3,7 @@ id: types
 title: Types
 ---
 
-LIGO is strongly and statically typed. This means that the compiler checks your program at compilation time and makes sure there won't be any type related runtime errors. LIGO types are built on top of Michelson's type system.
+LIGO is strongly and statically typed. This means that the compiler checks your program at compilation time and makes sure there won't be any type related runtime errors. LIGO types are built on top of Michelson's type system. 
 
 ## Built-in types
 
@@ -36,6 +36,8 @@ let dog_breed: animal_breed = "Saluki";
 
 <!--END_DOCUSAURUS_CODE_TABS-->
 
+> Types in LIGO are `structural`, which means that `animalBreed`/`animal_breed` and `string` are interchangable and are considered equal.
+
 ## Simple types
 <!--DOCUSAURUS_CODE_TABS-->
 <!--Pascaligo-->
@@ -146,3 +148,18 @@ let ledger: account_balances =
 ```
 
 <!--END_DOCUSAURUS_CODE_TABS-->
+
+## Annotations
+
+In certain cases, type of an expression cannot be properly determined. This can be circumvented by annotating an expression with it's desired type, here's an example:
+
+<!--DOCUSAURUS_CODE_TABS-->
+<!--Pascaligo-->
+```pascaligo
+type int_map is map(int, int);
+function get_first(const int_map: int_map): option(int) is int_map[1]
+// empty map needs a type annotation
+const first: option(int) = get_first(((map end) : int_map ));
+```
+
+<!--END_DOCUSAURUS_CODE_TABS-->

gitlab-pages/website/package-lock.json

@@ -5624,15 +5624,6 @@
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@@ -7412,15 +7403,6 @@
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       "dev": true
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@@ -7750,6 +7732,12 @@
         "picomatch": "^2.0.4"
       }
     },
+    "reason-highlightjs": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/reason-highlightjs/-/reason-highlightjs-0.2.1.tgz",
+      "integrity": "sha512-DWWPtfeQjwKgHj2OOieEIAB544uAVjwOAIAg2Yu09CobdUe41Yah0Z67GEvmVtpYCGG/+3CZvDRM1hMVr1zN3A==",
+      "dev": true
+    },
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@@ -9433,12 +9421,6 @@
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