[Lwip] draft-ietf-lwig-minimal-esp shepherd writeup

I am now preparing the shepherd writeup for draft-ietf-lwig-minimal-esp. 
I wanted to clarify and double check a few things:

- If the SPI is not random and is chosen by some application specific 
method -> it can reveal the application using ESP.

- I assume a resource-constrained device would not have many inbound 
connections. Would it make sense to generate a byte of randomness 
instead of entire 32-bit SPI? At least some APIs allow asking for a byte 
of randomness (randomByte()). This is assuming an upper limit on the 
number of inbound connections.

- When sequence numbers are time -> won't it reveal the time at which 
the packet was sent.

- Are we comfortable with the recommendation: 'A node MAY drop 
anti-replay protection provided by IPsec, and instead implement its own 
internal mechanism.'? What might this internal mechanism look like?

A few typos:

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Section 3:

Please expand SAD on first usage.

Section 4:

Typo: In a constrainted environment -> In a constrained environment

I looked at old RFCs and they seem to use both crypto-suite and 
cryptosuite. I have a preference for the later. Perhaps we can remove 
the hyphen.

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--Mohit