Move pages under tldr, lint run.sh, update docs

tldr/base64

@@ -0,0 +1,25 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# base64
+
+> Encode or decode file or `stdin` to/from Base64, to `stdout`.
+> More information: <https://www.gnu.org/software/coreutils/base64>.
+
+- Encode the contents of a file as base64 and write the result to `stdout`:
+
+`base64 {{path/to/file}}`
+
+- Decode the base64 contents of a file and write the result to `stdout`:
+
+`base64 --decode {{path/to/file}}`
+
+- Encode from `stdin`:
+
+`{{somecommand}} | base64`
+
+- Decode from `stdin`:
+
+`{{somecommand}} | base64 --decode`