Documentation: Example build commands fail after examples removed from default-members

[tanish111]

Describe the bug
Examples were removed from the default build, so the documentation is now outdated. Commands in the README (such as those using cargo build --example ...) no longer work as written.

To Reproduce
Steps to reproduce the behavior:

1. Navigate to the examples directory.
2. Run:
   cargo build --release --example servers_counter_stdio

Expected behavior
The example servers_counter_stdio should build successfully using the command provided in the documentation.

Logs

(base) tanishdesai37@Tanishs-MacBook-Air examples % cargo build --release --example servers_counter_stdio

error: no example target named `servers_counter_stdio` in default-run packages
help: available example in `mcp-server-examples` package:
    servers_counter_stdio

Additional context
This issue started after #541, when examples were removed from default-members to avoid macOS linker errors. As a result, example targets no longer build using the old documentation commands. We need to update the documentation.

[tanish111]

@alexhancock @johnw188 Do you think we should remove the examples/README.md? Since each example folder (servers/wasi/…) already includes instructions that work as expected.