Bump browserslist from 4.15.0 to 4.16.6 in /docs (paritytech#398)

Bumps [browserslist](https://github.com/browserslist/browserslist) from 4.15.0 to 4.16.6.
- [Release notes](https://github.com/browserslist/browserslist/releases)
- [Changelog](https://github.com/browserslist/browserslist/blob/main/CHANGELOG.md)
- [Commits](browserslist/browserslist@4.15.0...4.16.6)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/yarn.lock

@@ -1850,15 +1850,15 @@ browserify-zlib@^0.2.0:
     pako "~1.0.5"
 
 browserslist@^4.0.0, browserslist@^4.12.0, browserslist@^4.14.5, browserslist@^4.14.7:
-  version "4.15.0"
-  resolved "https://registry.yarnpkg.com/browserslist/-/browserslist-4.15.0.tgz#3d48bbca6a3f378e86102ffd017d9a03f122bdb0"
-  integrity sha512-IJ1iysdMkGmjjYeRlDU8PQejVwxvVO5QOfXH7ylW31GO6LwNRSmm/SgRXtNsEXqMLl2e+2H5eEJ7sfynF8TCaQ==
+  version "4.16.6"
+  resolved "https://registry.yarnpkg.com/browserslist/-/browserslist-4.16.6.tgz#d7901277a5a88e554ed305b183ec9b0c08f66fa2"
+  integrity sha512-Wspk/PqO+4W9qp5iUTJsa1B/QrYn1keNCcEP5OvP7WBwT4KaDly0uONYmC6Xa3Z5IqnUgS0KcgLYu1l74x0ZXQ==
   dependencies:
-    caniuse-lite "^1.0.30001164"
-    colorette "^1.2.1"
-    electron-to-chromium "^1.3.612"
+    caniuse-lite "^1.0.30001219"
+    colorette "^1.2.2"
+    electron-to-chromium "^1.3.723"
     escalade "^3.1.1"
-    node-releases "^1.1.67"
+    node-releases "^1.1.71"
 
 buffer-from@^1.0.0:
   version "1.1.1"
@@ -2030,10 +2030,10 @@ caniuse-api@^3.0.0:
     lodash.memoize "^4.1.2"
     lodash.uniq "^4.5.0"
 
-caniuse-lite@^1.0.0, caniuse-lite@^1.0.30001109, caniuse-lite@^1.0.30001164:
-  version "1.0.30001164"
-  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30001164.tgz#5bbfd64ca605d43132f13cc7fdabb17c3036bfdc"
-  integrity sha512-G+A/tkf4bu0dSp9+duNiXc7bGds35DioCyC6vgK2m/rjA4Krpy5WeZgZyfH2f0wj2kI6yAWWucyap6oOwmY1mg==
+caniuse-lite@^1.0.0, caniuse-lite@^1.0.30001109, caniuse-lite@^1.0.30001219:
+  version "1.0.30001230"
+  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30001230.tgz#8135c57459854b2240b57a4a6786044bdc5a9f71"
+  integrity sha512-5yBd5nWCBS+jWKTcHOzXwo5xzcj4ePE/yjtkZyUV1BTUmrBaA9MRGC+e7mxnqXSA90CmCA8L3eKLaSUkt099IQ==
 
 caseless@~0.12.0:
   version "0.12.0"
@@ -2236,10 +2236,10 @@ color@^3.0.0:
     color-convert "^1.9.1"
     color-string "^1.5.4"
 
-colorette@^1.2.1:
-  version "1.2.1"
-  resolved "https://registry.yarnpkg.com/colorette/-/colorette-1.2.1.tgz#4d0b921325c14faf92633086a536db6e89564b1b"
-  integrity sha512-puCDz0CzydiSYOrnXpz/PKd69zRrribezjtE9yd4zvytoRc8+RY/KJPvtPFKZS3E3wP6neGyMe0vOTlHO5L3Pw==
+colorette@^1.2.1, colorette@^1.2.2:
+  version "1.2.2"
+  resolved "https://registry.yarnpkg.com/colorette/-/colorette-1.2.2.tgz#cbcc79d5e99caea2dbf10eb3a26fd8b3e6acfa94"
+  integrity sha512-MKGMzyfeuutC/ZJ1cba9NqcNpfeqMUcYmyF1ZFY6/Cn7CNSAKx6a+s48sqLqyAiZuaP2TcqMhoo+dlwFnVxT9w==
 
 combined-stream@^1.0.6, combined-stream@~1.0.6:
   version "1.0.8"
@@ -2995,10 +2995,10 @@ ee-first@1.1.1:
   resolved "https://registry.yarnpkg.com/ee-first/-/ee-first-1.1.1.tgz#590c61156b0ae2f4f0255732a158b266bc56b21d"
   integrity sha1-WQxhFWsK4vTwJVcyoViyZrxWsh0=
 
-electron-to-chromium@^1.3.612:
-  version "1.3.614"
-  resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.3.614.tgz#ff359e8d2249e2ce859a4c2bc34c22bd2e2eb0a2"
-  integrity sha512-JMDl46mg4G+n6q/hAJkwy9eMTj5FJjsE+8f/irAGRMLM4yeRVbMuRrdZrbbGGOrGVcZc4vJPjUpEUWNb/fA6hg==
+electron-to-chromium@^1.3.723:
+  version "1.3.739"
+  resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.3.739.tgz#f07756aa92cabd5a6eec6f491525a64fe62f98b9"
+  integrity sha512-+LPJVRsN7hGZ9EIUUiWCpO7l4E3qBYHNadazlucBfsXBbccDFNKUBAgzE68FnkWGJPwD/AfKhSzL+G+Iqb8A4A==
 
 elliptic@^6.5.3:
   version "6.5.4"
@@ -5170,10 +5170,10 @@ node-libs-browser@^2.2.1:
     util "^0.11.0"
     vm-browserify "^1.0.1"
 
-node-releases@^1.1.67:
-  version "1.1.67"
-  resolved "https://registry.yarnpkg.com/node-releases/-/node-releases-1.1.67.tgz#28ebfcccd0baa6aad8e8d4d8fe4cbc49ae239c12"
-  integrity sha512-V5QF9noGFl3EymEwUYzO+3NTDpGfQB4ve6Qfnzf3UNydMhjQRVPR1DZTuvWiLzaFJYw2fmDwAfnRNEVb64hSIg==
+node-releases@^1.1.71:
+  version "1.1.72"
+  resolved "https://registry.yarnpkg.com/node-releases/-/node-releases-1.1.72.tgz#14802ab6b1039a79a0c7d662b610a5bbd76eacbe"
+  integrity sha512-LLUo+PpH3dU6XizX3iVoubUNheF/owjXCZZ5yACDxNnPtgFuludV1ZL3ayK1kVep42Rmm0+R9/Y60NQbZ2bifw==
 
 nopt@1.0.10:
   version "1.0.10"