Update README.md

@@ -6,7 +6,7 @@
 - 미세먼지 정보뿐만 아니라 일반 날씨 정보도 제공
 
 ## Installation
-1. Get a free API Key at [here](#사용한-외부-api)
+1. Get a free API Key at [here](#external-api)
 2. Clone the repo
 ```sh
 git clone ssh://git@khuhub.khu.ac.kr:12959/2017103956/howsTheAir.git
@@ -25,7 +25,7 @@ git clone ssh://git@khuhub.khu.ac.kr:12959/2017103956/howsTheAir.git
 }
 
 
-## 사용한 외부 API
+## external API
 - [kakao map api](https://apis.map.kakao.com/)
 - [google map api](https://cloud.google.com/maps-platform/?utm_source=google&utm_medium=cpc&utm_campaign=FY18-Q2-global-demandgen-paidsearchonnetworkhouseads-cs-maps_contactsal_saf&utm_content=text-ad-none-none-DEV_c-CRE_396485513010-ADGP_Hybrid+%7C+AW+SEM+%7C+SKWS+~+Maps+%7C+BMM+%7C+Mapping+APIs-KWID_43700049560642328-kwd-412104684431-userloc_1009871&utm_term=KW_%2Bmap%20%2Bapis-ST_%2Bmap+%2Bapis&gclid=EAIaIQobChMIhtfai66Q6gIVRJ_CCh3Qqw_BEAAYASAAEgKLd_D_BwE)
 - [대기오염정보](https://www.data.go.kr/tcs/dss/selectApiDataDetailView.do?publicDataPk=15000581)