docs(userspace/libsinsp/filter/parser): fix grammar doc #7329

Job	Run time
build-libs-linux-amd64-static 🎃	23m 11s
build-libs-linux-amd64 😁 (system_deps)	7m 16s
build-shared-libs-linux-amd64 🧐	5m 39s
build-libs-linux-amd64 😁 (bundled_deps)	16m 55s
build-libs-emscripten 🧐	5m 37s
build-libs-others-amd64 😨 (windows-latest, MultiThreaded)	5m 50s
build-libs-linux-amd64 😁 (system_deps_minimal)	6m 0s
build-shared-libs-macos-amd64 😨	1m 16s
build-libs-others-amd64 😨 (windows-latest, MultiThreadedDLL)	5m 22s
build-libs-linux-amd64 😁 (sanitizers)	17m 27s
build-libs-others-amd64 😨 (macos-latest)	2m 50s
build-libs-linux-amd64 😁 (zig)	24m 33s
build-libs-linux-arm64 😁 (system_deps)	12m 51s
run-e2e-tests-amd64 (system_deps)	9m 16s
build-libs-linux-arm64 😁 (bundled_deps)	29m 39s
build-libs-linux-arm64 😁 (system_deps_minimal)	9m 46s
test-libs-static (bundled_deps)	13m 49s
run-e2e-tests-amd64 (bundled_deps)	19m 6s
build-libs-linux-arm64 😁 (sanitizers)	32m 36s
run-e2e-tests-amd64 (asan)	20m 40s
build-libs-linux-arm64 😁 (zig)	41m 15s
	5h 10m 54s

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