examples : update wasm examples to include server.py [no ci] (#2908)

This commit updates the README files for the wasm examples to include
instructions on how to run the examples using the provided server.py
which was included in Commit 6e8242f
("examples : command.wasm updates (#2904)").

The motivation for this is consistency with the command.wasm example.

Author: danbev

examples/bench.wasm/README.md

@@ -15,7 +15,17 @@ cd whisper.cpp
 mkdir build-em && cd build-em
 emcmake cmake ..
 make -j
+```
+The example can then be started by running a local HTTP server:
+```console
+python3 examples/server.py
+```
+And then opening a browser to the following URL:
+http://localhost:8000/bench.wasm
 
+To run the example in a different server, you need to copy the following files
+to the server's HTTP path:
+```
 # copy the produced page to your HTTP path
 cp bin/bench.wasm/*       /path/to/html/
 cp bin/libbench.worker.js /path/to/html/

examples/stream.wasm/README.md

@@ -13,7 +13,17 @@ cd whisper.cpp
 mkdir build-em && cd build-em
 emcmake cmake ..
 make -j
+```
+The example can then be started by running a local HTTP server:
+```console
+python3 examples/server.py
+```
+And then opening a browser to the following URL:
+http://localhost:8000/stream.wasm
 
+To run the example in a different server, you need to copy the following files
+to the server's HTTP path:
+```
 # copy the produced page to your HTTP path
 cp bin/stream.wasm/*       /path/to/html/
 cp bin/libstream.worker.js /path/to/html/

examples/whisper.wasm/README.md

@@ -35,7 +35,17 @@ cd whisper.cpp
 mkdir build-em && cd build-em
 emcmake cmake ..
 make -j
+```
+The example can then be started by running a local HTTP server:
+```console
+python3 examples/server.py
+```
+And then opening a browser to the following URL:
+http://localhost:8000/whisper.wasm
 
+To run the example in a different server, you need to copy the following files
+to the server's HTTP path:
+```
 # copy the produced page to your HTTP path
 cp bin/whisper.wasm/*    /path/to/html/
 cp bin/libmain.worker.js /path/to/html/