doc/INSTALL: correct some typos

A double `git` and a `mode`.

doc/INSTALL.md

@@ -24,7 +24,7 @@ For actually doing development and running the tests, you will also need:
 * pip3: to install python-bitcoinlib
 * valgrind: for extra debugging checks
 
-You will also need a version of bitcoind with segregated witness and `estimatesmartfee` economical node, such as the 0.16 or above.
+You will also need a version of bitcoind with segregated witness and `estimatesmartfee` with `ECONOMICAL` mode support, such as the 0.16 or above.
 
 To Build on Ubuntu
 ---------------------
@@ -37,7 +37,7 @@ Get dependencies:
     sudo apt-get install -y \
       autoconf automake build-essential git libtool libgmp-dev \
       libsqlite3-dev python python3 python3-mako net-tools zlib1g-dev libsodium-dev \
-      git gettext
+      gettext
 
 If you don't have Bitcoin installed locally you'll need to install that
 as well: