Bump terser from 4.8.0 to 4.8.1 in /docs (paritytech#783)

Bumps [terser](https://github.com/terser/terser) from 4.8.0 to 4.8.1.
- [Release notes](https://github.com/terser/terser/releases)
- [Changelog](https://github.com/terser/terser/blob/master/CHANGELOG.md)
- [Commits](https://github.com/terser/terser/commits)

---
updated-dependencies:
- dependency-name: terser
  dependency-type: indirect
...

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

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

docs/yarn.lock

@@ -2049,9 +2049,9 @@ browserslist@^4.0.0, browserslist@^4.12.0, browserslist@^4.14.5, browserslist@^4
     node-releases "^1.1.71"
 
 buffer-from@^1.0.0:
-  version "1.1.1"
-  resolved "https://registry.yarnpkg.com/buffer-from/-/buffer-from-1.1.1.tgz#32713bc028f75c02fdb710d7c7bcec1f2c6070ef"
-  integrity sha512-MQcXEUbCKtEo7bhqEs6560Hyd4XaovZlO/k9V3hjVUF/zwW7KBVdSK4gIt/bzwS9MbR5qob+F5jusZsb0YQK2A==
+  version "1.1.2"
+  resolved "https://registry.yarnpkg.com/buffer-from/-/buffer-from-1.1.2.tgz#2b146a6fd72e80b4f55d255f35ed59a3a9a41bd5"
+  integrity sha512-E+XQCRwSbaaiChtv6k6Dwgc+bx+Bs6vuKJHHl5kox/BaKbhiXzqQOwK4cO22yElGp2OCmjwVhT3HmxgyPGnJfQ==
 
 buffer-indexof@^1.0.0:
   version "1.1.1"
@@ -7038,9 +7038,9 @@ source-map-resolve@^0.5.0, source-map-resolve@^0.5.2:
     urix "^0.1.0"
 
 source-map-support@~0.5.12:
-  version "0.5.19"
-  resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.19.tgz#a98b62f86dcaf4f67399648c085291ab9e8fed61"
-  integrity sha512-Wonm7zOCIJzBGQdB+thsPar0kYuCIzYvxZwlBa87yi/Mdjv7Tip2cyVbLj5o0cFPN4EVkuTwb3GDDyUx2DGnGw==
+  version "0.5.21"
+  resolved "https://registry.yarnpkg.com/source-map-support/-/source-map-support-0.5.21.tgz#04fe7c7f9e1ed2d662233c28cb2b35b9f63f6e4f"
+  integrity sha512-uBHU3L3czsIyYXKX88fdrGovxdSCoTGDRZ6SYXtSRxLZUzHg5P/66Ht6uoUlHu9EZod+inXhKo3qQgwXUT/y1w==
   dependencies:
     buffer-from "^1.0.0"
     source-map "^0.6.0"
@@ -7388,9 +7388,9 @@ terser-webpack-plugin@^1.4.3:
     worker-farm "^1.7.0"
 
 terser@^4.1.2:
-  version "4.8.0"
-  resolved "https://registry.yarnpkg.com/terser/-/terser-4.8.0.tgz#63056343d7c70bb29f3af665865a46fe03a0df17"
-  integrity sha512-EAPipTNeWsb/3wLPeup1tVPaXfIaU68xMnVdPafIL1TV05OhASArYyIfFvnvJCNrR2NIOvDVNNTFRa+Re2MWyw==
+  version "4.8.1"
+  resolved "https://registry.yarnpkg.com/terser/-/terser-4.8.1.tgz#a00e5634562de2239fd404c649051bf6fc21144f"
+  integrity sha512-4GnLC0x667eJG0ewJTa6z/yXrbLGv80D9Ru6HIpCQmO+Q4PfEtBFi0ObSckqwL6VyQv/7ENJieXHo2ANmdQwgw==
   dependencies:
     commander "^2.20.0"
     source-map "~0.6.1"