Update Integration Specification with clarifying language (#405)

* Add clarifying verbiage for SRAM initialization requirements by SoC

* Formatting for Table 17 - adjust whitespace and escape underscores

* Edited per review feedback

* Remove redundant verbiage around SRAM init

* threat model to lower case

* Clarify PAUSER integration requirements in table

* Update description on generic input wires to clarify unused bits should be grounded

* Grammar tweaks

* Grammar changes from review