[site/docs] Add software READMEs

Make software more prominent in the documentation.
There are sporadic links to sw, make the existence clearer.

Signed-off-by: Tobias Wölfel <tobias.woelfel@mailbox.org>
diff --git a/sw/README.md b/sw/README.md
index b540f9c..359dabc 100644
--- a/sw/README.md
+++ b/sw/README.md
@@ -4,7 +4,7 @@
 
 ## Building
 
-OpenTitan software is built using [Meson](https://mesonbuild.com), although OpenTitan's project structure is sufficiently ideosyncratic that we use a custom workflow.
+OpenTitan software is built using [Meson](https://mesonbuild.com), although OpenTitan's project structure is sufficiently idiosyncratic that we use a custom workflow.
 
 For example, to build the OpenTitan executable located at `sw/device/examples/hello_world` for FPGA, run the following commands:
 ```console