Change license, add Makefile, add image caching control

1 files changed, 4 insertions, 2 deletions

diff --git a/source/know/concept/rutherford-scattering/index.md b/source/know/concept/rutherford-scattering/index.md
index 6f5a21f..edf391c 100644
--- a/source/know/concept/rutherford-scattering/index.md
+++ b/source/know/concept/rutherford-scattering/index.md
@@ -19,7 +19,8 @@ Let 2 be initially at rest, and 1 approach it with velocity $$\vb{v}_1$$.
 Coulomb repulsion causes 1 to deflect by an angle $$\theta$$,
 and pushes 2 away in the process:
 
-{% include image.html file="two-body-full.png" width="50%" alt="Two-body repulsive 'collision'" %}
+{% include image.html file="two-body-full.png" width="50%"
+    alt="Two-body repulsive 'collision'" %}
 
 Here, $$b$$ is called the **impact parameter**.
 Intuitively, we expect $$\theta$$ to be larger for smaller $$b$$.
@@ -67,7 +68,8 @@ then by comparing $$t > 0$$ and $$t < 0$$
 we can see that $$v_x$$ is unchanged for any given $$\pm t$$,
 while $$v_y$$ simply changes sign:
 
-{% include image.html file="one-body-full.png" width="60%" alt="Equivalent one-body deflection" %}
+{% include image.html file="one-body-full.png" width="60%"
+    alt="Equivalent one-body deflection" %}
 
 From our expression for $$\vb{r}$$,
 we can find $$\vb{v}$$ by differentiating with respect to time: