Create a `doc/GLOSSARY.md` file to define common terms used in the fuzzer

[devdanzin]

We currently use a lot of jargon without much in the way of explanation. Having a glossary helps users and developers understand the docs and code. Here's a possible initial implementation:

# Lafleur Glossary

## A

**AST (Abstract Syntax Tree)**: A tree representation of the syntactic structure of Python code. Lafleur operates on ASTs rather than raw text to ensure syntactically valid mutations.

## C

**Child/Mutant**: A test case created by applying mutations to a parent test case.

**Corpus**: The collection of interesting test cases that have discovered unique coverage.

**Coverage Edge**: A transition between two micro-operations (uops) in the JIT trace, representing control flow.

## E

**Evolutionary Fuzzing**: A fuzzing approach where test cases evolve over time through mutation and selection based on fitness (coverage).

## H

**Harness**: A function that executes the test logic in a loop to trigger JIT compilation.

**Havoc**: A mutation strategy that applies many random transformations to create significantly different code.

## J

**JIT (Just-In-Time) Compiler**: CPython's experimental compiler that converts hot Python bytecode into machine code.

## L

**Lineage**: The chain of parent-child relationships from a test case back to its original seed.

**Lineage Coverage**: The union of all coverage discovered by a test case and all its ancestors.

## M

**Mutation**: A transformation applied to a test case to create a new variant.

## P

**Parent**: A test case selected from the corpus to be mutated.

## R

**Rare Event**: A JIT trace event that indicates unusual behavior (bailouts, failures, etc.).

## S

**Seed**: An initial test case, either generated by fusil or provided manually.

**Spam**: A mutation strategy that repeatedly applies the same transformation type.

**Sterile**: A parent that has been mutated many times without producing new coverage.

## T

**Test Case**: A Python script that exercises JIT behavior.

## U

**Uop (Micro-operation)**: A low-level operation in CPython's JIT intermediate representation.

Feel free to add more entries or modify suggested ones.