docs: the PowerShell commands run as written

[DemchaAV]

Why

Two pages hand Windows readers a command that fails.

PowerShell splits a -D flag whose property name contains a dot. Probed directly:

python -c "import sys; print(sys.argv[1:])" -Dmdep.outputFile=x -DincludeScope=test -Dexec.mainClass=Foo
['-Dmdep', '.outputFile=x', '-DincludeScope=test', '-Dexec', '.mainClass=Foo']

Maven then rejects the fragment with Unknown lifecycle phase ".mainClass=…". A flag
without a dot before the = survives, which is why this is easy to miss.

examples/README.md also told readers "The same mvnw.cmd form works on Windows
PowerShell with backslash paths." It does not. The bash block above it ends a line with
\, which PowerShell has no notion of — it runs ./mvnw alone and then looks for a
command named -Dexec.mainClass=…. And the backslash-paths advice pointed at a
non-problem: forward slashes work fine in -f.

docs/operations/benchmarks.md quotes the flags on its java lines and missed the one
on its mvnw line, so the page half-knew.

What

• examples/README.md: replaces the false claim with the PowerShell command, one line,
  flag quoted, and says what goes wrong without each change.
• docs/operations/benchmarks.md: quotes -Dmdep.outputFile=… and states the rule,
  pointing at the java lines below that already follow it.

Tests

Every command in the diff was run on this machine's PowerShell, before and after:

Command	As documented	Fixed
examples/README.md run-one-example	BUILD FAILURE, Unknown lifecycle phase ".mainClass=…"	PS_EXIT=0, wrote module-first-profile.pdf
benchmarks.md build-classpath	BUILD FAILURE	BUILD SUCCESS, wrote benchmarks/target/benchmark.classpath

./mvnw -B -ntp clean verify → BUILD SUCCESS.