update structure and readme and add area

README.md

@@ -1,8 +1,29 @@
-Install, in "development mode", so any change in the local repo is effective:
+# Features
+
+commands
+- `eng-area`: area of a simple polygon
+- `eng-awg`: diameter/area from AWG wire size
+- `eng-beam`: calculate mechanical beam eigen-frequencies
+- `eng-plate`: central deflection and min. thickness of a circular plate
+- `eng-tube`: bubkling stress of a tube
+
+libs
+- `engineering.area.area(vertices)`
+- `engineering.awg.diameter(number)`
+- `engineering.awg.area(number)`
+- `engineering.beam.eigen_frequency_fixed_free(n, E, I, rho, A, L)`
+- `engineering.plate.deflection_pinned(p, r, nu, E, t)`
+- `engineering.plate.deflection_clamped(p, r, nu, E, t)`
+- `engineering.plate.thickness_min(p, d, Rp02, S)`
+- `engineering.plate.allowable_stress(sigma, S)`
+
+
+# Install
+In "development mode", so any change in the local repo is effective:
 
     python -m pip install --editable git+<url>#egg=engineering --src=$HOME/repos --prefix=$HOME/.local --break-system-packages
 
 
-Uninstall:
+# Uninstall
 
     python -m pip uninstall engineering --break-system-packages