[Bugfix] Mobile platform builds (#11)

This PR contains the work done to address the issue #10, that was raised based on the build logs from publishing the package in the Swift Package Index.

To provide further details about the work done:
- [x] fixed the `Router` protocol that was causing a compilation issue on *watchOS* platforms;
- [x] downgraded the swift tools version in the `Package` file to v5.5;
- [x] bumped the minimum platform version in the `Package` file to restrict support to the last 2 major releases;
- [x] written the *Installation* section in the `README` file;
- [x] updated the project logo assets, including light and dark versions;
- [x] updated the project logo in the `README` file and added support for both light and dark modes.

Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Reviewed-on: #11

Sources/Coordination/Protocols/Router.swift

@@ -10,7 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if canImport(UIKit)
+#if canImport(UIKit) && !os(watchOS)
 import UIKit
 #endif
 
@@ -23,7 +23,7 @@ public protocol Router: AnyObject {
     
     // MARK: Functions
     
-    #if canImport(UIKit)
+    #if canImport(UIKit) && !os(watchOS)
     /// Present a view controller animatedly or not, depending on the given `animated` parameter, and also pass a closure that should be called on dismissal.
     /// - Parameters:
     ///   - viewController: A `UIViewController` view controller instance to present.
@@ -42,7 +42,7 @@ public protocol Router: AnyObject {
     
 }
 
-#if canImport(UIKit)
+#if canImport(UIKit) && !os(watchOS)
 // MARK: - Router+Implementations
 
 public extension Router {