Corrected capitalization, corrected to American spellings and typos (#30685)

* Translate challenge subtitles and example challenge text to Spanish

* Corrected errors in syntax and punctuation

* Multiple corrections of it/s to its plus other grammar corrections

* Correction and added paragraph to CSS Flex article

* Corrected my own typo

* Corrected capitalization, American spellings and typos

guide/english/computer-science/databases/key-value-databases/index.md

@@ -45,7 +45,7 @@ Here are some examples of databases that use the key-value approach:
 - [Oracle NoSQL Database](https://www.oracle.com/database/nosql/index.html)
 - [Cassandra](http://cassandra.apache.org) (hybrid between key-value and column-oriented databases)
 - [Voldemort](http://www.project-voldemort.com/voldemort/)
-- [Consul KV store](https://www.consul.io/intro/getting-started/kv.html) (a tool with it's own key-value store)
+- [Consul KV store](https://www.consul.io/intro/getting-started/kv.html) (a tool with its own key-value store)
 
 #### More Information:
 * Key-value databases on [Wikipedia](https://en.wikipedia.org/wiki/Key-value_database)

guide/english/computer-science/dynamic-programming/index.md

@@ -5,7 +5,7 @@ title: Dynamic Programming
 ## Dynamic Programming
 
 Dynamic Programming(DP) is a programming technique for solving problems where the computations of its subproblems overlap: you write your program in a way that avoids recomputing already solved problems.
-This technique, it's usually applied in conjunction with memoization which is an optimization technique where you cache previously computed results, and return the cached result when the same computation is needed again.
+This technique is usually applied in conjunction with memoization which is an optimization technique where you cache previously computed results, and return the cached result when the same computation is needed again.
 
 An example with Fibonacci's series which is defined as:
 

guide/english/computer-science/garbage-collection/index.md

@@ -21,7 +21,7 @@ In .net programming, heap has three generations called generation 0, 1, 2. Gener
 
 Generations 1 and 2 has object which has the longer life time. GC on generations 1 and 2 will not happen until the generations 0 has sufficient memory to allocate.
 
-Its not advisable to invoke the GC programmatically. It's good to let it happend on its own. GC get call whenever the generation 0 gets filled. GC will not impact the performance of your program. 
+Its not advisable to invoke the GC programmatically. It's good to let it happen on its own. GC gets called whenever the generation 0 gets filled. GC will not impact the performance of your program. 
 
 Garbage collection is the process in which programs try to free up memory space that is no longer used by variables, objects, and such.  Garbage collection is implemented differently for every language. Most high-level programming languages have some sort of garbage collection built in. Low-level programming languages may add garbage collection through libraries.