Add a podspec

CaptureKit.podspec

@@ -0,0 +1,14 @@
+Pod::Spec.new do |s|
+    s.name = 'CaptureKit'
+    s.version = '1.0.0'
+    s.license = 'MIT'
+    s.summary = 'A screen capture framework'
+    s.homepage = 'https://github.com/space-code/capture-kit'
+    s.authors = { 'Nikita Vasilev' => '[email protected]' }
+    s.source = { :git => 'https://github.com/space-code/capture-kit.git', :tag => s.version }
+    s.documentation_url = 'https://github.com/space-code/capture-kit'
+
+    s.osx.deployment_target = '10.12'
+
+    s.source_files = 'CaptureKit/CaptureKit.h'
+end