Cosmetic: Fix a number of typos, no functional changes.

Fix various misspellings of things like "environment", "kernel",
"default" and "volatile", and throw in a couple grammar fixes.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
diff --git a/board/sbc8349/README b/board/sbc8349/README
index 2c35919..e2d60cc 100644
--- a/board/sbc8349/README
+++ b/board/sbc8349/README
@@ -50,7 +50,7 @@
     trying to preserve your old environment settings and user flash).
   - Set the start address of the erase/flash process to FF80_0000
   - Set the target RAM required to 64kB.
-  - Select sectors for erasing (see note on enviroment below)
+  - Select sectors for erasing (see note on environment below)
   - Select Erase and Reprogram.
 
 Note that some versions of the register files used with Workbench