Minor edits.

README.md

@@ -29,7 +29,9 @@ botwiki](https://botwiki.org/tutorials/how-to-create-a-twitter-app/).
 
 Put your adsbexchange.com API key and twitter keys in `secrets.yaml`.
 
-Create an initial history database: `echo '{}' > advisory-circular.db`
+Create an initial history database:
+
+`echo '{}' > advisory-circular.db`
 
 Install node dependencies:
 
@@ -58,11 +60,11 @@ do
 done
 ```
 
-* Do not run the script with a large radius, or adsbexchange.com will
-  ban your IP. I use a radius of 40 miles.
+* **Do not run the script with a large radius, or adsbexchange.com will
+  ban your IP.** I use a radius of 40 miles.
 
-* Do not run the script more ofen than once every 10 seconds, or
-  adsbexchange.com will ban your IP.
+* **Do not run the script more ofen than once every 10 seconds, or
+  adsbexchange.com will ban your IP.**
 
 
 ## To do
@@ -80,7 +82,7 @@ done
       passed around for a decade.
 - [ ] Add type information to tweet status, e.g. "Eurocopter AS350".
 - [ ] Use Wikipedia graph to rank landmarks? More inbound links to a
-      page = higher significance?
+      page means it has higher significance?
 - [ ] Add support for Mastodon/ActivityPub.
 - [ ] Generate our own maps instead of using adsbx's? The adsbx map
       isn't always in sync with the data from the API.