HPCC-10143 Corrections to ECL documentation

Spelling and grammar corrections to ecl/eclcc/DOCUMENTATION.rst

Only obvious spelling corrections to the jotted notes:
ecl/hqlcpp/codegen.txt
ecl/hqlcpp/transforms.txt

Signed-off-by: jamienoss <james.noss@lexisnexis.com>
Merge pull request #4915 from jamienoss/issue10143-ECLCC-Docs

HPCC-10143 Corrections to ECL documentation

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>