docs: fix a few typos

Noticed a couple, found the rest using vimspell.

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/docs/install.html b/docs/install.html
index 765ecea..0808194 100644
--- a/docs/install.html
+++ b/docs/install.html
@@ -178,7 +178,7 @@
 
 <p>
 In order to achieve that one should update their local manifest to point to the
-upstream repo, set the approapriate BOARD_GPU_DRIVERS and build the
+upstream repo, set the appropriate BOARD_GPU_DRIVERS and build the
 libGLES_mesa library.
 </p>