feat(docs): add markdown linter for exercises README.md files

.github/workflows/lint.yml

@@ -0,0 +1,18 @@
+name: Lint
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: DavidAnson/markdownlint-cli2-action@v9
+        with:
+          globs: "exercises/**/*.md"

.markdownlint.yml

@@ -0,0 +1,2 @@
+# MD013/line-length Line length, Expected: 80
+MD013: false

exercises/conversions/README.md

@@ -6,6 +6,7 @@ The simplest form of type conversion is a type cast expression. It is denoted wi
 
 Rust also offers traits that facilitate type conversions upon implementation. These traits can be found under the [`convert`](https://doc.rust-lang.org/std/convert/index.html) module.
 The traits are the following:
+
 - `From` and `Into` covered in [`from_into`](from_into.rs)
 - `TryFrom` and `TryInto` covered in [`try_from_into`](try_from_into.rs)
 - `AsRef` and `AsMut` covered in [`as_ref_mut`](as_ref_mut.rs)
@@ -17,5 +18,6 @@ These should be the main ways ***within the standard library*** to convert data
 ## Further information
 
 These are not directly covered in the book, but the standard library has a great documentation for it.
+
 - [conversions](https://doc.rust-lang.org/std/convert/index.html)
 - [`FromStr` trait](https://doc.rust-lang.org/std/str/trait.FromStr.html)

exercises/hashmaps/README.md

@@ -1,4 +1,5 @@
 # Hashmaps
+
 A *hash map* allows you to associate a value with a particular key.
 You may also know this by the names [*unordered map* in C++](https://en.cppreference.com/w/cpp/container/unordered_map),
 [*dictionary* in Python](https://docs.python.org/3/tutorial/datastructures.html#dictionaries) or an *associative array* in other languages.

exercises/options/README.md

@@ -2,6 +2,7 @@
 
 Type Option represents an optional value: every Option is either Some and contains a value, or None, and does not.
 Option types are very common in Rust code, as they have a number of uses:
+
 - Initial values
 - Return values for functions that are not defined over their entire input range (partial functions)
 - Return value for otherwise reporting simple errors, where None is returned on error

exercises/smart_pointers/README.md

@@ -1,4 +1,5 @@
 # Smart Pointers
+
 In Rust, smart pointers are variables that contain an address in memory and reference some other data, but they also have additional metadata and capabilities.
 Smart pointers in Rust often own the data they point to, while references only borrow data.
 

exercises/traits/README.md

@@ -7,13 +7,13 @@ Data types can implement traits. To do so, the methods making up the trait are d
 In this way, traits are somewhat similar to Java interfaces and C++ abstract classes.
 
 Some additional common Rust traits include:
+
 - `Clone` (the `clone` method)
 - `Display` (which allows formatted display via `{}`)
 - `Debug` (which allows formatted display via `{:?}`)
 
 Because traits indicate shared behavior between data types, they are useful when writing generics.
 
-
 ## Further information
 
 - [Traits](https://doc.rust-lang.org/book/ch10-02-traits.html)