[v3] Update Markdown files to latest spec

concepts/callbacks/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on callbacks concept

concepts/callbacks/introduction.md

@@ -1 +1,3 @@
+# Introduction
+
 TODO: add introduction for callbacks concept

concepts/errors-basic/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on errors-basic concept

concepts/errors-basic/introduction.md

@@ -1 +1,3 @@
+# Introduction
+
 TODO: add introduction for errors-basic concept

concepts/futures/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on futures concept

concepts/futures/introduction.md

@@ -1,3 +1,5 @@
+# Introduction
+
 TODO: the content below is copied from the exercise introduction and probably needs rewriting to a proper concept introduction
 
 ## futures

concepts/iterables-basic/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on iterables-basic concept

concepts/iterables-basic/introduction.md

@@ -1 +1,3 @@
+# Introduction
+
 TODO: add introduction for iterables-basic concept

concepts/numbers-basic/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on numbers-basic concept

concepts/numbers-basic/introduction.md

@@ -1,3 +1,5 @@
+# Introduction
+
 TODO: the content below is copied from the exercise introduction and probably needs rewriting to a proper concept introduction
 
 ## numbers-basic

concepts/recursion/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on recursion concept

concepts/recursion/introduction.md

@@ -1 +1,3 @@
+# Introduction
+
 TODO: add introduction for recursion concept

concepts/strings-basic/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on strings-basic concept

concepts/strings-basic/introduction.md

@@ -1,3 +1,5 @@
+# Introduction
+
 Strings are useful for holding data that can be represented in text form. Some
 of the most-used operations on strings are to check their `length`, to build
 and concatenate them using the `+` and `+=` string operators, checking for the

concepts/type-conversion/about.md

@@ -1 +1,3 @@
+# About
+
 TODO: add information on type-conversion concept

concepts/type-conversion/introduction.md

@@ -1,3 +1,5 @@
+# Introduction
+
 TODO: the content below is copied from the exercise introduction and probably needs rewriting to a proper concept introduction
 
 ## numbers-basic

docs/ABOUT.md

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+# About
+
 Dart brings object-oriented and typing together with the flexibility that JavaScript is known for.  It is designed to simplify common programming tasks. In recent years, its popularity in the software development community has grown tremendously.
 
 To dig deeper into Dart, [click here](https://www.dartlang.org/guides/language/language-tour).

docs/INSTALLATION.md

@@ -1,3 +1,5 @@
+# Installation
+
 ## Installing Dart
 
 ### Automatic installation instructions (recommended)

docs/LEARNING.md

@@ -1,4 +1,4 @@
-## Recommended Learning Resources
+# Recommended Learning Resources
  * [Dart Language Overview](https://www.dartlang.org/guides/language/language-tour)
  * [Getting Started](https://www.dartlang.org/tutorials/dart-vm/get-started)
  * [Make a command line app](https://www.dartlang.org/tutorials/dart-vm/cmdline)

exercises/concept/futures/.docs/hints.md

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+# Hints
+

exercises/concept/futures/.docs/instructions.md

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+# Instructions
+

exercises/concept/futures/.docs/introduction.md

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+# Introduction
+

exercises/concept/numbers/.docs/hints.md

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+# Hints
+

exercises/concept/numbers/.docs/instructions.md

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+# Instructions
+

exercises/concept/numbers/.docs/introduction.md

@@ -1,3 +1,5 @@
+# Introduction
+
 ## Numbers Basic
 
 ## Type Conversion

exercises/concept/strings/.docs/hints.md

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+# Hints
+

exercises/concept/strings/.docs/instructions.md

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+# Instructions
+

exercises/concept/strings/.docs/introduction.md

@@ -1,3 +1,5 @@
+# Introduction
+
 Strings are useful for holding data that can be represented in text form. Some
 of the most-used operations on strings are to check their `length`, to build
 and concatenate them using the `+` and `+=` string operators, checking for the

exercises/practice/phone-number/.docs/instructions.append.md

@@ -1,4 +1,4 @@
-## Tip
+# Tip
 
 A function with a *return type* can only return data of that *type* and `null`.
 However the function caller is only expecting one data type.