Add tutorial READMEs and fix tutorial return codes

Add README.md files for moeo/tutorial/Lesson{1-4}, smp/tutorial/Lesson{1-4},
and mo/tutorial/Lesson9 — these tutorials had no documentation.

Fix return 1 → return 0 in 28 tutorial main() functions across mo/ and
smp/ that unconditionally returned failure status.

moeo/tutorial/Lesson2/README.md

@@ -0,0 +1,31 @@
+# Multi-objective EA on the flow-shop scheduling problem
+
+This lesson solves a more realistic combinatorial problem: the bi-objective
+permutation flow-shop, which minimizes both makespan and total flow time.
+
+## Running
+
+From the `build/moeo/tutorial/Lesson2` directory:
+
+```shell
+./FlowShopEA @FlowShopEA.param
+```
+
+The parameter file specifies the problem instance, population size, operator
+rates, and fitness assignment strategy.
+
+## How it works
+
+The code uses ParadisEO's `do_make_*` factory functions to build all
+components from command-line parameters:
+
+```c++
+eoEvalFuncCounter<FlowShop>& eval = do_make_eval(parser, state);
+eoInit<FlowShop>& init = do_make_genotype(parser, state);
+eoGenOp<FlowShop>& op = do_make_op(parser, state);
+```
+
+The flow-shop representation is defined in `FlowShop.h` — a
+permutation-based `moeoVector` with a bi-objective vector. Different
+Pareto-based fitness assignment strategies (NSGA-II, SPEA2, IBEA, etc.)
+can be selected via parameters.