docs(userspace/libsinsp/filter/parser): fix grammar doc #7327

Job	Run time
build-libs-linux-amd64 😁 (system_deps)	4m 27s
build-libs-linux-amd64 😁 (bundled_deps)	4m 27s
build-libs-linux-amd64-static 🎃	4m 28s
build-libs-linux-amd64 😁 (system_deps_minimal)	4m 28s
build-libs-linux-amd64 😁 (sanitizers)	4m 22s
build-libs-others-amd64 😨 (windows-latest, MultiThreaded)	4m 30s
build-libs-linux-amd64 😁 (zig)	4m 26s
build-libs-others-amd64 😨 (windows-latest, MultiThreadedDLL)	4m 28s
build-libs-linux-arm64 😁 (system_deps)	4m 24s
build-libs-others-amd64 😨 (macos-latest)	3m 0s
build-shared-libs-linux-amd64 🧐	4m 40s
build-libs-linux-arm64 😁 (bundled_deps)	4m 24s
build-libs-linux-arm64 😁 (system_deps_minimal)	3m 26s
build-libs-emscripten 🧐	4m 41s
build-libs-linux-arm64 😁 (sanitizers)	4m 23s
build-libs-linux-arm64 😁 (zig)	3m 12s
build-shared-libs-macos-amd64 😨	2m 8s
run-e2e-tests-amd64 (system_deps)	4m 31s
run-e2e-tests-amd64 (bundled_deps)	4m 36s
test-libs-static (bundled_deps)	4m 35s
run-e2e-tests-amd64 (asan)	4m 34s
	1h 28m 10s

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