fish: add mkcd and mansearch

fish/functions/mansearch.fish

@@ -0,0 +1,4 @@
+function mansearch --description 'Full-text search of man pages'
+    # -F is used to match literally (no regex)
+    command rg -z -F $argv (manpath | string split :) -l | command sed -r 's@.*/(.*)\.([0-9]+)(\.gz)?@\1(\2)@g'
+end

fish/functions/mkcd.fish

@@ -0,0 +1,3 @@
+function mkcd --description 'Create and cd into a directory'
+    mkdir -p $argv[1] && cd $argv[1]
+end