Add description for System/Mutation Flow Diagrams

System diagram arrows are annotated with numbers and each one has description now.
Mutation Workflow also has description for each step.

Change-Id: I2cf96931cd4d9ac47c93ffb4b7e06adc96c7b314
Reviewed-on: http://review.couchbase.org/34336
Reviewed-by: Sriram Melkote <siri@couchbase.com>
Tested-by: Sriram Melkote <siri@couchbase.com>
Tested-by: Pratap Chakravarthy <pratapsrc@gmail.com>
List of terms and definitions used in secondary index.

worked on John's comment.

Change-Id: Icd5df40f1c79863d5b205e6dd4e0010a8b8fd9f5
Reviewed-on: http://review.couchbase.org/34262
Reviewed-by: Sriram Melkote <siri@couchbase.com>
Tested-by: Sriram Melkote <siri@couchbase.com>
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Reviewed-by: Pratap Chakravarthy <pratapsrc@gmail.com>
Merge branch 'master' of github.com:couchbase/indexing
IndexManager writeup.