added OTel podspecs (#591)

OpenTelemetryApi.podspec

@@ -0,0 +1,24 @@
+Pod::Spec.new do |spec|
+  spec.name = "OpenTelemetryApi"
+  spec.version = "1.10.1"
+  spec.summary = "Swift OpenTelemetryApi"
+
+  spec.homepage = "https://github.com/open-telemetry/opentelemetry-swift"
+  spec.documentation_url = "https://opentelemetry.io/docs/languages/swift"
+  spec.license = { :type => "Apache 2.0", :file => "LICENSE" }
+  spec.authors = "OpenTelemetry Authors"
+
+  spec.source = { :git => "https://github.com/open-telemetry/opentelemetry-swift.git", :tag => spec.version.to_s }
+  spec.source_files = "Sources/OpenTelemetryApi/**/*.swift"
+
+  spec.swift_version = "5.9"
+  spec.ios.deployment_target = "13.0"
+  spec.tvos.deployment_target = "13.0"
+  spec.watchos.deployment_target = "6.0"
+
+  # This is necessary because we use the `package` keyword to access some properties in `OpenTelemetryApi`
+  # This keyword was introduced in Swift 5.9 and it's tightly bound to SPM.
+  # To provide the correct values to the flags `-package-name` and `-module-name` we checked out the outputs from:
+  # `swift build --verbose`
+  spec.pod_target_xcconfig = { "OTHER_SWIFT_FLAGS" => "-module-name OpenTelemetryApi -package-name opentelemetry_swift" }
+end

OpenTelemetrySdk.podspec

@@ -0,0 +1,20 @@
+Pod::Spec.new do |spec|
+  spec.name = "OpenTelemetrySdk"
+  spec.version = "1.10.1"
+  spec.summary = "Swift OpenTelemetrySDK"
+
+  spec.homepage = "https://github.com/open-telemetry/opentelemetry-swift"
+  spec.documentation_url = "https://opentelemetry.io/docs/languages/swift"
+  spec.license = { :type => "Apache 2.0", :file => "LICENSE" }
+  spec.authors = "OpenTelemetry Authors"
+
+  spec.source = { :git => "https://github.com/open-telemetry/opentelemetry-swift.git", :tag => spec.version.to_s }
+  spec.source_files = "Sources/OpenTelemetrySdk/**/*.swift"
+
+  spec.swift_version = "5.9"
+  spec.ios.deployment_target = "13.0"
+  spec.tvos.deployment_target = "13.0"
+  spec.watchos.deployment_target = "6.0"
+
+  spec.dependency 'OpenTelemetryApi', spec.version.to_s
+end