docs: correcting links to antithesis external docs

Author: twlim-antithesis

README.md

@@ -5,4 +5,4 @@ This library provides methods for C++ programs to configure the [Antithesis](htt
 * Randomness functions for requesting both structured and unstructured randomness from the Antithesis platform.
 * Lifecycle functions that inform the Antithesis environment that particular test phases or milestones have been reached.
 
-For general usage guidance see the [Antithesis C++ SDK Documentation](https://antithesis.com/docs/using_antithesis/sdk/cpp/overview.html)
+For general usage guidance see the [Antithesis C++ SDK Documentation](https://antithesis.com/docs/using_antithesis/sdk/cpp/overview/)

antithesis_instrumentation.h

@@ -7,7 +7,7 @@ This header file can be used in both C and C++ programs. (The rest of the SDK wo
 
 You should include it in a single .cpp or .c file.
 
-The instructions (such as required compiler flags) and usage guidance are found at https://antithesis.com/docs/using_antithesis/sdk/cpp/overview.html.
+The instructions (such as required compiler flags) and usage guidance are found at https://antithesis.com/docs/using_antithesis/sdk/cpp/overview/.
 */
 
 #include <unistd.h>

antithesis_sdk.h

@@ -2,7 +2,7 @@
 
 // This header file contains the Antithesis C++ SDK, which enables C++ applications to integrate with the [Antithesis platform].
 //
-// Documentation for the SDK is found at https://antithesis.com/docs/using_antithesis/sdk/cpp/overview.html.
+// Documentation for the SDK is found at https://antithesis.com/docs/using_antithesis/sdk/cpp/overview/.
 
 #include <cstdint>
 #include <random>