renamed certbot_from_git variable to certbot_install_from_source and fixed some wording

tasks/install-from-source.yml

@@ -7,7 +7,7 @@
     update: "{{ certbot_keep_updated }}"
     force: yes
 
-- name: Set Certbot script variable
+- name: Set Certbot script variable.
   set_fact:
     certbot_script: "{{ certbot_dir }}/certbot-auto"
 

tasks/install-with-package.yml

@@ -1,7 +1,7 @@
 ---
-- name: Install Certbot
+- name: Install Certbot.
   package: name=certbot state=present
 
-- name: Set Certbot script variable
+- name: Set Certbot script variable.
   set_fact:
     certbot_script: certbot

tasks/main.yml

@@ -1,9 +1,9 @@
 ---
-- include: install-from-package.yml
-  when: not certbot_from_git
+- include: install-with-package.yml
+  when: not certbot_install_from_source
 
-- include: install-from-git.yml
-  when: certbot_from_git
+- include: install-from-source.yml
+  when: certbot_install_from_source
 
 - include: renew-cron.yml
   when: certbot_auto_renew