docs: Enhance FSM page with state transition table, symbol explanation and Moore vs Mealy comparison

[VaibhavJindal7]

Description

While studying the FSM page I found several important
sections missing that would help students understand
FSMs better.

Missing Content

1. No explanation of state label symbols
   (M0, W5, W10 etc.)
2. No explanation of what 00, 01, 10 means
   on transition arrows
3. No state transition table for vending machine
4. No Moore vs Mealy comparison table
5. The number "20" shown inside every circle
   in the diagram is never explained anywhere

File

docs/seq-design/fsm.md

[VaibhavJindal7]

I would like to work on this issue.
I have already studied the FSM page thoroughly
and identified all the missing sections.
I will submit a PR shortly.

[VaibhavJindal7]

Update — Quiz section added to PR

I have added a quiz section at the end of the FSM page
covering the following topics:

1. Moore vs Mealy difference
2. Number of flip-flops needed for N states
3. Reading a state transition table
4. Identifying FSM type from a diagram
5. Mealy to Moore machine conversion

The quiz follows the same format used in other pages
of the Interactive Book such as encoders-decoders.md
using the {:.quiz} syntax.