History for ServiceModel

Revisions
@Lukas Eisenhauer Lukas Eisenhauer on 13 Dec 2022 : add comment on requests
@Lukas Eisenhauer Lukas Eisenhauer on 13 Dec 2022 : add reference to request system call
@Lukas Eisenhauer Lukas Eisenhauer on 13 Dec 2022 : add functions description
@Lukas Eisenhauer Lukas Eisenhauer on 13 Dec 2022 : fix <> brackets
@Lukas Eisenhauer Lukas Eisenhauer on 13 Dec 2022 : add service model page