Update git submodules

* Update docs/submodules/sdc.git from branch 'master'
  to 5b1f9a16f823c31d26f9306ea1ee540120f6780e
  - Add alter_tables.cql to gitignore
    
    The alter_tables.cql is being copied during build and should be ignored.
    
    Change-Id: I0a0a420e17761247a6575ad8715ccbd20fd5c1e1
    Issue-ID: SDC-2640
    Signed-off-by: andre.schmid <andre.schmid@est.tech>
    
1 file changed