Improve the docs

• Add some info about the RESCONFIG_LOC environment variable and the default location of resconfig in this sesction.
• In this section this is outdated: "With the option Engine name you can give the engine a name. If no name is specified then a unique name (a UUID) will be generated.". In the same stion in the note: "Python dictionaries use in the Python API" should be "Python dictionaries used in the Python API"